Does that make sense? Fight or flight is going to kick in and despite their enhanced reflexes and whatnot I find it hard to believe that somebody who just gets koed by a modern Nuke and somebody who can dish out 30 megatons and take it to the face are going to react sa me as people who would be vaporised.
Superman and Thor aren't the types to try and blitz anyway. Thor plays around and has fun with his fights, while Clark tries to reason with his opponents and doesn't fight until he's pushed too or get pissed. However, Xavier will mind rape them in an instant, or at least freeze them. He's done it like 4-5 times through all the movies.
He even erased Moira's memories because he thought it was best. He could turn them into toddlers in their heads.