I can understand the motivation for acting on death threats like someone claiming they would like to stab another person. Who knows how plausible that is? Without knowing much about the poster, you kind of have to assume the most plausible interpretation in a lot of settings.

Launching someone in a rocket to space is clearly beyond the reach of any single individual. It's also not particularly violent in the scheme of things. It's clearly intended to be hyperbole, and hyperbole against a public figure is common. Musk himself, despite his thin skin, has often said much worse, I guess his ban from Twitter should be coming any day now?