Actually, it's quite the contrary. If he is having problems (and as age sets in, they all do) and his wife's career is a failure, and his son is a failure, it is exactly what he would do, in public and to express his alpha male dominance to reassume the honor of his pathetic family. Think about it, its like adding injury to insult, Rock is pointing out that she's not really sought after and the medical condition resulting in the "GI Jane look" , is sign of weakness for them. Whether it makes her want him more sexually is irrelevant. They've already passed that point, sex is not the thing. Alpha male dominance and feeling powerful from that slap, in front of everyone, that's his thing. I said "so he can have some dignity when he looks at her in bed" what that actually means is; "in the house he wants live with his pride intact" He needed to assert his dominance over the situation and he did.