Playing in the D League is questioned because he could be making so much more money overseas, but here is the thing:

He has made somewhere in the range of $10M in his life already, and hasn't turned 27 yet. He has a good 10 years of playing time left. If he can play more than half the games in another NBA season, he will vest in the NBA's retirement program. Why not play in the D League this year, and even next, to try and land one more season in the NBA (or just half a season)? If he does, he gets automatic income in retirement and has that much less to worry about in his future. If he somehow finds a fit, he plays another 3-5 years in the NBA and makes a bunch more $. If he doesn't he can still play a minimum of 5 years overseas and make a few million dollars more. If he can stretch that to 8 overseas, he might make close to another $10M. I think it's a good call on his part to give this a shot. Good on him for trying to keep his NBA dream alive.