I think they played Rusty James once. And only Billie and Jason did, so maybe that’s why it was acoustic, they weren’t in a proper “Green Day” gig. I have no idea how they or any other bands choose the songs, if they go by their favorites or the ones they think will be more fun to play. Knowing Green Day, maybe some day they’ll play Rusty James full band, like they’ve been doing with songs they never played before or played very few times.
(Long answer and I couldn’t say something concrete, so sorry if it doesn’t help you) :-)