What life sentence? He's not in prison. However, your actions follow you around forever, that's the way the world works. Is it a "life sentence" if a guy fails three training events and can't get hired at "the majors"? No, it's a rational assessment of whether or not he will perform his duties effectively and safely.
This is 100% settled Law...employers have every right to discriminate against potential employees for that Permanent Record you were warned about in 3rd grade. So the question is simply whether or not hiring a convicted violent felon, however reformed he may or may not be, is a good play on the odds. And, as @PilotFighter points out, it's pretty obviously not.