The injury wasn't BS. He missed Raw the night after Wrestlemania because he flew home to his own personal doctor to have surgery since he tore his abdominal muscle wrestling John Cena. He couldn't risk letting the injury mess with his movie schedule (i.e. his full-time job.)
I wouldn't bet on The Rock making Wrestlemania XXX. His already busy schedule for the upcoming year doesn't look like it's gonna allow for it. I think he probably will have one more match at some point in the future, though. Personally, I'd be fine with him just staying retired from in-ring competition and instead just be inducted into the 2014 Hall Of Fame. If they want the biggest induction possible for their big milestone 30th Wrestlemania, then The Rock is the #1 guy to induct. Maybe he can free himself up for that much at least.