Not exactly a fuzzy guard situation, but rather this can be reacted to. Superman doesn't have a terribly fast F3 and if you know to look for it you can block it, since you're only waiting to see if he starts winding up rather than going for low laser.
That said, this is actually pretty much a true 50/50 online, because lag will dramatically reduce your effective ability to react. I've had people do it to me online before and just... ugh.