I... just don't understand your confusion? Of course it's a "hit piece". There's a market for hit pieces because there are people willing to pay to see content aimed at their favorite targets. And the trailer starts with Musk sniping to substantiate what it's about and clarify who its for.

Maybe it's that you think "hit piece" means "illigitimate?". Documentary cinema is absolutely allowed to have perspective. Musk's own communication is hardly unbiased or coolly considered, and he's been known to engage in some "creative advocacy" of his own. Would you apply the same logic there?

My own opinion is that he's a complicated guy and a seemingly textbook bipolar case with a lot of good technical instincts and a really destructive egomaniacal streak. He could do with some hit pieces, honestly.