It's a bit complicated on my part. My family really had no ground to guilt me about moving off. If they wanted us in the US, they had their chance to help us with that. But ultimately, us coming here turned out to be the better option, IMO.
Before my mom died last year, she always was a bit negative about the UK. She would make comments. Not really bad ones. Little ones. Like when I described the way my MiL had the laundry set up when I first moved here (washing machine, spin dryer which you had to hold in one place by leaning on it, condenser dryer which took forever), she assumed that was the way you did laundry here. Like we went out and banged our clothes against rocks or something (not that there's anything wrong with that). I don't know anyone else here who still uses a spin dryer, but I couldn't convince mom of that.
Or she'd say stuff like "Don't you get bored with British TV?" No. At the time we didn't have anything but Freeview, and it still seemed better (at least in quality) than the cable I paid for back home. And missing British telly is on the con list for moving into Europe or beyond. One day I went somewhere on a train and I talked to mom later in the day. I mentioned that a few people on the train weren't wearing any deodorant and some lady insisted on closing all the windows. Of course, this could happen anywhere, but mom was all "Oh, I couldn't stand it." She said that about a lot of things about the UK. I got to the point where it stopped bothering me. Sure she missed me, but she also loved to travel. She always said she regretted not doing more of it. I think that it was more sour grapes than anything.
I can't imagine people putting their love of their country over their love of their children. I am assuming you're an adult, and your opinions aren't his duty to shape or correct. I am guessing he's dealing with the upcoming loss more than anything.