They're only legal if you're Republican.
Kathy Griffin got blacklisted+investigated for holding up a fake severed Trump head.
https://www.npr.org/2019/04/23/716258113/kathy-griffin-life-after-the-trump-severed-head-controversy
But be a Republican politician making death threats and the DOJ will wrist slap you. It's quite clear the bias our DOJ has always had. Other countries like Canada consider some of our extremists terrorists, and we're still handing them baby sentences for an insurrection.
Except they don't. They get demonetization from literally breathing from Google who treats them like shit, so it's best to donate to their patreons anyway.