Yeah, you're probably right about it making sense in canon. I can see Sam wanting to volunteer with them for those reasons. Just - there didn't seem to be any awareness on the part of the show that they were implicitly promoting a homophobic organization, which really came across poorly.

The episode should have just been a 40 min b&w variety show/start wars/judy garland special with more songs and Puck Puckerman teaching them all about Hanukkah.

This is a first-rate opinion and you should feel great about it. Especially that last part. Now I'm craving an episode where Puck narrates the story of Hanukkah and the glee kids act it out (with singing too, ofc).