Getting a green card would presumably reduce his border hassles. On the flip side it would require him to file US taxes as long as he retains it no matter where

Getting a green card would presumably reduce his border hassles. On the flip side it would require him to file US taxes as long as he retains it no matter where he lives. In my case even with that I got hassled every time - multi hour delays on every arrival because of something screwed up in their records of me. Eventually I went so far as to get citizenship because of the hassle. That requires me to file US taxes for the rest of my life even if I choose to permanently reside outside the US.