You can't expect to be employed by a company while simultaneously building a personal brand around publicly criticizing that company. I'm surprised Google tried to work with him for so long before removing him from the company.
He didn't just try to blow the whistle with his disclosure. He's been doing media tours and joining a lot of different podcasts. I suspect Google is sitting on a long list of clear disclosure policy violations and, from the sounds of it, even gave him a chance to reign in his policy breaking before they finally cut him loose.
It also becomes difficult to trust someone when their position stops being one of (supposed) moral responsibility and starts becoming a source of fame, celebrity, and access to influential podcast/media circles that were previously out of reach.