It’s pretty clear from the narration of events that he and his team (this story is from the 1980s, when O’Brien was a member of the infamous Harvard Lampoon) succeeded. I don’t think that they were planning to keep Burt Ward’s Robin costume; in fact, I’m getting the impression that Ward thought that this entire thing was both hysterical, and flattering (I’d say that it was both, myself).
I have no idea why I wanted to get this on the record, either. It’s just been kind of bugging me.