Conservatives and right-wingers are the only acceptable target.
Why do you think Kimmel tried to characterize the killer as MAGA? Because he can't joke about him being gay, having a troon boyfriend, being antifa, not even about being a furry. Mocking right-wingers, even if they were victims of murder is considered safe comedy
Back in the 90s, it was pretty cheap or even free to go into the audiences. They were always looking for seat fillers. I can’t imagine how bad it was before Kibble got canned.