The negativity is because he's using investor money in xAI in a related party transaction. He's negotiating both sides of the sale and it's not at all obvious the transaction price is a good or real price for Twitter. It may make sense to merge the two, but this is an unethical way to make a deal and I think it is likely the xAI investors are getting screwed.
I can understand that angle, but TBH, I have a hard time caring. They aren't a public company, and their private shareholders aren't lacking for resources to fight if they disagreed with this choice.
Oh yeah I totally agree with that framing. I find this fascinating intellectually because of the deal dynamics and worthy of critique but agree that the tone of some of the commentary is a bit silly. It's a really unethical thing to do, but it's all private capital and everyone with exposure knowingly made the choice to go into business with Musk. They can sue and definitely will win if Musk did cross any legal lines.
What makes it unethical? For all we know, the private investors are all in agreement on this. Musk tends to take capital from investors that he is on very good terms with. There's most likely a lot of overlap between investors of both companies.