miller (a.k.a. trivialknot) asks the question (regarding Christmas music): "[I]f [some social] gain requires coercively harming a minority, is it truly worthwhile?"
"Harm" and "coercion" are subjective terms: we cannot talk about "harm" without talking about how a person feels about something; we cannot talk about coercion without talking about will and consent, so their will can be coercively violated without their consent. These terms are also morally loaded. "Harm" is morally unacceptable negativity; coercion is morally unacceptable force. So the question as its stands is trivial or circular: unacceptable actions are unacceptable. In a morally neutral sense, a person is harmed if and only if they subjectively feel that they have been harmed, and they are coerced if and only if they subjectively feel that they have been coerced. The only way to detect harm and coercion is to ask people. (We also need to discover whether or not the objectively determinable actions they claim to have been harmful or coercive actually occurred.)
We could, of course, define harm and coercion objectively. However, such an objective definition would include and exclude actions as harmful and coercive only according to our a priori moral beliefs about actions. The best we can do with objective definitions is to talk about consistency, not correctness. Thus, miller's question would be, "Is ubiquitous Christmas music substantively similar to other things we consider coercively harmful (morally unacceptable), and substantively different from things we do not consider coercively harmful (morally acceptable)." Ubiquitous Christmas music cannot intrinsically be coercively harmful; in a morally neutral sense, it is coercively harmful if and only if people subjectively feel like they are being coercively harmed. In other words, we cannot examine the objective characteristics of ubiquitous Christmas music, ignoring how people feel about it, and come to a moral determination.
(You may disagree with the above paragraph. Most philosophers who advocate deontic and objective moral philosophy would disagree. I would welcome any argument that's less circular than "subjective moral philosophy is not objective," or, "subjective moral philosophy is contradictory when interpreted objectively.")
There are also the subjectively reflective definitions of "coercion" and "harm": I believe you have been coerced or harmed if you subjectively feel you have been coerced or harmed, and I subjectively feel you have been coerced or harmed, and both of us believe so in an objectively consistent way (i.e. I believe that all objectively similar actions are also coercive or harmful). Again, we can still have a morally neutral reflective definition: the reflective definitions just distinguish between actions that a some people consider coercive or harmful, and actions that almost everyone considers coercive or harmful. For example, a lot of people believe that affording secular (non-religious) marriage to gay people is neither coercive nor harmful, even if a lot of religious people feel coerced or harmed by secular gay marriage. There's an argument that people who feel coerced or harmed by secular gay marriage do not feel like they are coercing or harming Muslims, for example, by eating pork. However, this objective inconsistency can be eliminated by admitting that in a morally neutral sense, eating pork does coercively harm Muslims, and so what?
Again, if we define coercive harm in a morally neutral sense, then by definition saying that some action requires coercive harm (in the subjectively reflective sense) is not saying that it is therefore, and for that reason only, morally unacceptable. We would have to add the statement as a premise, not a conclusion. However, adding the premise entails unresolvable contradictions in our present physical circumstances.
It is not (perhaps not yet) the case that everyone can have and do everything they want, and people who don't get or do what they want have a tendency to feel coercively harmed, especially when they don't get what they want because other people with superior power (either numbers, privilege, or violence) do get or do what they want. So we have to make trade-offs entailing morally neutral coercive harm: trade-offs are a physical necessity. Of course, if we can choose between harming no one and harming someone, most people (besides sadists) would agree the former is preferable. But a lot of social choices, including not only whether to play Christmas music ubiquitously for a month or two but also most criminal and property law, requires trading off coercive harm against some people to benefit others.
Let's consider a trade-off with, to most 21st century Americans, a subjectively obvious answer: chattel slavery of black people. The existence of chattel slavery requires unambiguous subjectively reflective coercive harm to slaves. The slaves themselves feel coercively harmed, and if free white people were in the same situation, they would feel coerced and harmed, so at some level they agree that slavery is coercively harmful. On the other hand, the abolition of chattel slavery requires unambiguous subjectively reflective coercive harm: the owners of slaves feel are harmed by the coercive deprivation of their property, and most 21st century Americans consider deprivation of property by force to be coercively harmful. (One could argue that people cannot be property, but "property" is just as subjective as "harm" and "coercion"; by deciding that people cannot be property, one embeds the moral judgment in the definition a priori. As a subjectivist, I think that embedding moral judgments in language is perfectly fine, so long as we're honest and upfront about it and do not pretend to be objective.) If we have the moral premise that if X entails coercively harming someone, then X is wrong, then both the preservation and abolition of chattel slavery is wrong. We could, of course, have the moral premise that if X is wrong, then its imposition is coercively harmful, and its abolition is not coercively harmful. But that renders the first premise vacuous: wrong things are wrong. Or we could say that when we have two choices that are coercively harmful, we have to just decide between them on some other basis.
And that is precisely what we did with chattel slavery, and what we do with Christmas music. Both alternatives are, in a morally neutral, subjectively reflective sense, coercively harmful (and the imposition of music can be a form of torture, arguably worse than the imposition of pain). We simply have to choose between them. How we do so is a matter for scientific inquiry; how we should do so is a matter of philosophical and political theoretical inquiry.