Yes, he's pissed at what he regarded as a fake announcement, which it might have been, though it could also have been many other things which he doesn't credit. And "Shitty way they were treated"? That could mean anything. It could mean my leading theory as to what any of them are on about, which is simply that Whedon was behaving like a director under a boatload of stress, and probably yelled a lot and generally acted like an ass to them. Which....isn't really news to anyone except maybe Fisher and possibly Mamoa. Hollywood is pretty well known for treating actors like crap.