Basically yes. Perhaps "problematic conduct with peers" is poor wording or maybe it refers to some harrassment crackdown or maybe it's due to financial problems, really it could be any number of things but because it's Tesla the union connection is what comes to mind. Regardless it's obvious they're firing people for something they don't want to be connected to and using 'performance' as a smoke screen.

That wouldn't make much sense, though. The last thing you'd want to do if you were trying to keep out a union is behave in a way your employees would see as tyrannical.

Well there's two opposite ways that have historically been tried to avoid unionisation - you can make sure employees are all happy enough not to want it, or make sure they're too scared of losing their jobs should they support it.