The nice thing about philosophy is that there aren't any rules--there can't be. If someone proposed some rules, then it would be a matter of interesting philosophical inquiry whether those rules were correct, or whether some other set of rules would be better. And by rules should we hold that discussion?
Even if a barefoot bum says the sun rises in the East, it's still true. I claim no credentials. I might in fact be an unemployed itinerant; I might have a PhD in Philosophy or Physics; I might be an ordinary guy with something to say.
Of course, if anything can be philosophy, then attaching the label doesn't have much value by itself. The only thing I can say about philosophy is that somehow or another every self-described work of philosophy should stand or fall on its own merits.