You think Google is the single company out there who is willing to employ you? How come?
Edit: Thinking about it, your comment actually made me more frustrated than I realized. I've been poor enough to having to be homeless at some points in my life, and yes, I've worked for immoral companies too, because I need food and shelter. But once you move up in life to the comfy jobs like software engineering, you don't have any excuse anymore that it's just about "feeding your family" when you literally have a sea of jobs available. It might be an excuse you tell yourself to justify your reasoning for getting paid more, but if you truly did care about it, you'd make a different choice, and still be able to feed your family, and I'm almost confident your family would be OK with you making that choice too, unless they also lack the empathy you seem to be missing.
You were homeless and didn't have a choice, so now obviously you're qualified to give assurances that essentially, "it is unlikely that your family will starve", right? /s
And if you're wrong, and shit hits the fan for whatever reason, who's going to fix that? You? No, he's going to have to fix that, because nobody else is going to step in.
It's easy to tell others that it's going to be OK, but put your money where your mouth is. Put $1M in a fund that he can access should he no longer be able to find employment. Then he'll have absolute certainty that it's going to be OK.
Something tells me you're not going to do that. Something tells me that what you would do if shit hits the fan, is you're going to tell him that he should find solace in the fact that while he's working for 1/5th of his former total comp, putting in more hours at the same time, seeing his kids less, not putting his kids through private school to give them the best chance at the best education, that, at least, some kid out there isn't watching 6-7 videos on the tablet that their parents use to do less parenting.
To be clear, I have no beef with Google the company and wouldn't mind working there again if it weren't in the ads division. After two years I transferred to the Chrome org and greatly enjoyed the work there. I was proud to develop something that is used the world over, it's open source, and I got to optimize tight code and tune for performance. (Yes, Chrome is fast, I don't understand the haters!) If I had just quit Google immediately, this wouldn't have happened and I would've missed out on a great experience.