In the episode "Wheels", why did that guy on the phone who called Burt say that Kurt was a fag?

because he was a stupid low life jerk.

Because he was an ignorant asshole.

Because he was being such an asshole.

so Burt can see that while he may except Kurt 100% not everyone will. and for Kurt to mostrar how selfless he can be. when he wants to

the kid was gay