If he wanted to invite you back stage, he would. I don’t know why you assume that’s what he wanted to do. It’s just guessing

Him thrusting his groin was a fairly common move on stage and in no way indicated he had romantic interest. Your jaw dropping isn’t an indication of you rejecting him and in no way would he perceived as such. He didn’t make any advances so there was nothing to reject.

Performers thrusting their body parts towards fans and audience (especially the ones that are obviously big fans) isn’t an indication of wanting blow jobs from total strangers in the audience.

Again we don’t know why he threw water at you. First it was a bottle but now you are saying it was few drops. Perhaps it was an accident. You’d need to ask him, although I am sure he doesn’t remember

I don’t know why you assign so many motives and agendas to other people’s (strangers) actions. Honestly none of them sound plausible and are very far fetched.