Brian sounds like the drag on the company, not Bob.
Bob is simply offering a deal that is in his best interests. Brian is the enabler, and I'm surprised HE wasn't fired.
Developers are expensive to recruit and train. If your department keeps losing them, because of the environment, then maybe you need a different environment.
Bob isn't just "offering a deal", he abused his position to try to get an employee fired and is blackmailing the company to force them to stay with BobX.