I can't speak to UC Irvine, but I know Hunter does the same thing with regard to not letting their admitted students speak about it in a public manner. I assumed it was because not all students that get in in the first round end up attending, so maybe they don't want non-first-round accepted applicants to feel like a second choice? IDK though. Maybe that's giving these schools too much credit. And it's not like everyone complies, because I've seen mentions of people being contacted for interviews with Hunter both here and in The Draft.