I think it's more important for the girls to be kept "quiet" after spaying than the little dudes. For girls, it's abdominal surgery; their innards got rearranged and they have a major incision. For the guys, it's simply a snip and a tuck ... in the scheme of things, it's not that big a deal (except to men

!)
I wouldn't want them playing fetch or running relays, if ya know what I mean, but if they feel UP to normal activity, they're probably OK. Just keep an eye on them.