Who’s he going to pick next?

This was not a random or petty attack. Their message on the bullet casings makes it clear they were attacking this person because they’ve knowingly helped enable incomprehensible amounts of human suffering on a scale of millions.

I understand that vigilantism, speaking generally, has its own serious dangers. But speaking specifically, this person is clearly not a threat to people who aren’t legalized mass murderers. Who’s he going to pick next? Probably the CEO of the second most abusive healthcare insurer.

That said, obviously with limited resources the police have to pick what cases take priority over others.

The police follow the law. The law is defined by politicians, who are effectively purchased by the owner class. The police were never going to arrest that CEO for their crimes against humanity, it would be illegal for them to do it out of the public interest. Direct vigilantism was the only realistic chance at deterrence in this situation.

because they’re too busy chasing down all those people who hurt others’ fee-fees by misgendering them

Weird fantasy but ok.