If you confess to a murder, the fact that your confession was protected First Amendment speech doesn't mean you shouldn't be convicted of murder. What's the difference between that and your example?

Proportionality, I would say, but I'm not from the US and don't know US (case) law so I might be way off here.

If a playwrite playing the lead character in their own production stands on stage and confesses to murder, surely that should be seen as part of the work and not a confession of the playwrite. When it comes to musicians doing the same thing, the US has a long history of selectively prosecuting black artists.

Producing art about a character committing a crime is different from admitting that you’d committed a crime. One is art, one is (hypothetically) an admission of guilt. That’s the difference.

Warrant picture shows 'trafficking in drugs', not making a song about weed. I am not sure about full context.

Don't forget the kidnapping!

I’m not sure if you’ve had much experience with American police, but having an accusation written on a warrant is rarely proof a crime actually occurred.

It's definitely a deterrent to saying certain things.