If the magic weakness was defined that way (which is not an opinion all writers share), then it would mostly likely BE written that he avoids getting hit using the various means at his disposal.
Can't have a dead Superman after all!
He'd probably be more likely to use some
super-speed in a fight like that than an average fight, but I don't see him fighting someone like Thor and not getting hit at all. Nor do I think that one blow from Mjolnir is likely to be lethal to him, even under writers who play up the magic weakness.