@snood,
Sorry to give wrong idea. That wasn't his plan. He said he could not vote for Sanders if he was the nominee but that he would continue as an activist to the end of getting dems elected in down ballot races. Thus it would be a consequence of one vote for the presidency but, hopefully, many more beneath.
As I said, he was not swayed even though I tried very hard. And I do find no (or little, I suppose) fault if anyone were to take that stance given continued activism. I've known the fellow for a long time. He's a good guy. I wasn't going to go to war with him as I don't want the good guys fighting each other.