I've no idea on this tbh, but it certainly wasn't to save paying a bonus.
Let's be extremely generous and say Jose was going to be due £1m in a bonus, I don't believe it was anything near that, but still let's say it was.
He's on £15m a year.
Levy sacks him and still has to pay him £15m a year, or at the very least, buy out his contract.
Levy then puts Mason in charge, basically free as he was here already.
But then he appoints Conte, also on £15m a year.
So now he's paying £30m a year and all to avoid a £1m bonus.
It simply doesn't make sense.
Obviously something happened behind the scenes, maybe a busy up, maybe the players were sick of him, maybe they went to Levy and asked for him to be sacked.
Something definitely did happen and the timing was extremely odd.