I think it is not a stretch to say that most humans would not choose to cause loved ones permanent, life-changing pain if it could be avoided simply by picking up a phone , leaving a forwarding address, etc. RG could relocate with all assets and maintain the relationship with his daughter as it had been going on and in due time, she would inherit his estate. If he loved his daughter, as you acknowledge, why would he walk away? We're back to that. It isn't going away.
I think in some ways it is easy to speak for "most humans," because most of us do not walk away from family, from retirement resources, from our homes and jobs. Lots of younger males don't support their children or participate in their lives--and clearly do not "love" them by any means. Or people divorce and have a second family and the first set of kids falls by the wayside. But RG was 60--who he was and how he treated people was well established by that time as predictable. observable life patterns. His connection to his daughter was not broken by divorce. They loved each other. So why would he hurt her in this way? Or hurt himself in this way? It just doesn't add up.
I don't see how people "give up" their reputation and experience. And in this economy, the ability to make money into one's seventies is a significant thing. Many attorneys and accountants have small practices well after retirement (my last 2 tax guys were both in their 70s). If RG wasn't planning to work immediately, he always had his expertise to fall back on if things changed. And the walkaway scenario leaves him with no income and no way to earn except in the underground economy (no ss#, no references, no work history).
So given all he had to walk away from, to give up, I wouldn't give walkaway a minute's thought without some motive--an uber-rich lover willing to support a guy in his 60s? evidence of a secret life (evidence, not speculation)? some indication that he was sick of the people around him and wanted out? A very smart psychologist told me once that most people have some sort of cost-benefit analysis going, even when they do stupid and irrational things, e.g.: The person on a diet eating the ice cream has traded long-range goals for short-term pleasure while another person would make the opposite choice. Even with denial and bargaining thrown in, there is some weighing of "what I get" vs "what I risk or give up." A person as old and smart as RG would have to do a lot of weighing before throwing away 60 years, his retirement security, a family, and his personal and professional identity. Even his family name. So what would he GET for giving those things up? I don't see any benefit, since he could get all of the "benefits" of walking away (if that is what they are) just by relocating (new sights, new place to live, no ties on a daily basis) or buying a Winnebago. And he'd have money to spend, medical insurance, and contact with his family when he wanted it. It would be a lot easier to start over in a new place as RG. All he had to do was retire and go wherever he wanted to go. But I am just repeating what I've said a hundred times.