Because if you're getting that pissed off about someone questioning anything about someone you like, my dude, then you're probably not just offended on their behalf.

[He taps the side of his head to imply this is a deeper thing. Usually, nobody gets that annoyed unless you think you're questioning something about them under all of it...or what they've made their foundation, in this case.]

People don't like hearing they pinned their flag onto something that's just the same as anything else.