Sorry, you are allowed to swear at a cop or stop [sic] on the flag and burn it... Those are constitutionally protected activities.
Spitting (which is what the song actually mentions) is assault. You're not allowed to do that to anyone.
And unless you actually own the flag that you are stomping on and burning, that's vandalism, also a crime. And even if you own it, you may still be committing a crime if you're careless about starting a fire where it could spread out of control.
Of course, you are lyingly dismissing the more significant crimes that the song actually mentions, in order to not just imply, but flat out lie by saying, that it only condemns
“constitutionally protected activities”
Sucker punch somebody on a sidewalk
Carjack an old lady at a red light
Pull a gun on the owner of a liquor store
But then, it's not as if anyone on this forum ever expects anything from you but lies, anyway.