I don’t think Trey Parker and Matt Stone could make their point any better:
Reaching by phone early Tuesday, Abu Talhah al Amrikee, the author of the post, said he wrote the entry to “raise awareness.” He said the grisly photograph of van Gogh was meant to “explain the severity” of what Parker and Stone did by mocking Muhammad.
“It’s not a threat, but it really is a likely outcome,” al Amrikee said, referring to the possibility that Parker and Stone could be murdered for mocking Muhammad. “They’re going to be basically on a list in the back of the minds of a large number of Muslims. It’s just the reality.”
Sounds like a threat to me. For context, they portrayed Muhammad in a bear costume, to make exactly this point.