Very, very strict. In fact since the rides at Universal are generally more intense than the ones at WDW, they are probably more strict. Height restrictions are there for a child's safety. If a too small kid gets on and gets hurt, parents can sue. No way is Universal going to take a chance of that. I've seen kids measured at the beginning of the line, then measured again by a different CM just prior to boarding. Even if they could make it past the first CM, the second CM should catch them.