The man became known as "Dan that swam 4 times". He was not dressed for a swim, much less 4 swims. He was borderline hypothermic. We told him to run the next rapid and if he swam again, we would build a fire, warm him up and walk him out. He ran the next rapid and then the next after that. He didn't swim the rest of the day. He did NOT have a fun day but was white knuckle paddling some really big water. But the lines were wide now, not creeky like before the confluence. He never paddled with us, on whitewater, again.
If this hasn't happened to you yet, it will. You always need to be prepared to make this decision, whether you are the one "in over their head" or it's one of your group. Dan was right to say what he did. We were probably wrong in our actions, it's hard to say since everything turned out OK.