They are offended. That's not a breach of the peace, nor is it a violation of their rights. How they react to that offense is their choice. "Up in arms"? Really? They're within their rights to bear them, certainly, but if they point them at their neighbor, it would constitute a threat.
And yes, this is classic passive-aggressive behavior.
Look up passive-aggressive.
Passive-aggressive behavior refers to passive ... resistance to authoritative instructions in interpersonal ... situations. Sometimes a method of dealing with stress or frustration, it results in the person attacking other people in subtle, indirect, and seemingly passive ways.
So, here we have this guy involved in a breach of the peace, offending people with his actions, acting in a passive-aggressive manner, and this is OK by you and your libertarian cronies. I suppose you'd say that we have no right not to be offended, huh?
But the flasher, whose actions also breach the peace, and alarm and offend others (legal definition), well, throw his a$$ in jail. Gee, looks like we DO have a right not to be offended.
Consistency is not your strong point, is it?