Getting rid of him over that was a really stupid move. Recasting an entire voice actor, after you've probably done a lot of work already, seems like a huge waste of time and resources.
Very, very few people were going to get upset that JonTron is voice acting a character despite their dislike for him. There's already thousands of stuffty people who have worked on things we play, watch, use, etc.
However, publicly announcing that you're removing a voice actor is practically PR Self Delete. I have never seen any other company just outright state that that they're replacing someone. And many companies probably do replace the people they hire. They just don't tell anyone, nor do they try and generate hype beforehand.
That all being said, you also shouldn't not buy the game just because they switched a voice actor. If it were going to be a fun game, it's still going to be a fun game. And don't try to hold a 'moral highground' on this by saying "i'm not going to buy this because i don't support what they did". Many, many other things you have probably bought were probably made by people who have done worse, and kept it behind closed doors. You will not be able to stop your money from going to people you disagree with. So don't be petty over a video game.