Without a written agreement that 'sympathy' would cost a lot... then again he could file his own small claims court suit - and maybe get a judgement that the deadbeats won't pay... Best to accept that good people always pay - (from the start) and people who offer excuses (for themselves) will always offer excuses.
In most all of the states he has no legal case. Some do allow for hand shake deals but proving it would be difficult and the expenses would beat out the money recouped. So, chalk it up to experience.
Personal story from long ago. A “friend” and I made a 15/30 reversse bet on two horses running at different tracks with our bookie. Both won, one horse went off at more than 20 to one, the other something like 4 to one. The result is we won over a K (big deal as I was making 100 a week). My “friend” collected on the bet and skipped. I told the book I would find him. The book said: how much did you lose? I said my share is 500+. He said again, how much did you lose? I said I lost nothing because we did not put the money up front. He said wise up, you learned a lesson, he is not your friend and it is not worth going to the clink for.