it's always fascinating when people want to find the line to when it's ok to be a jerk or not.
"This guy is a thief"
"Hey, don't say that about him. That's not cool"
"Why not? He once made fun of somebody for thinking the earth was flat."
"Yeah but that's not the same thing as accusing someone of a crime"
"Yeah but his friends made a joke about stealing something, same thing, right?"