Despite it being in the FAQ, all it actually says is that they try to cause as little performance loss as they could. No idea how much that is, or if people will turn it off to get a few frames back.
It does say that without a GPU the performance is considerable.
Because what he did wasn’t illegal. It was just wrong. They didn’t want anything to do with him any more, but he didn’t break the law and so they couldn’t use that part of the contract to terminate it.
They felt it was so wrong that they paid him $20mil to break that contract. They absolutely would have taken another option if it was viable.