The usher should not allow her to enter until she dresses appropriately. Who cares whether that flatters or disturbs the woman? It's not meant to be any type of compliment, rather it should embarrass or shame her but these days it probably won't. The point to be made clear to her and everyone is that she's not getting in dressed like that. Period.
See, this is precisely the over-reaction against Conciliar laxity that results in a leaven of the Pharisees being injected into Traddieland, and resulting in not a few walking away from the places with the vibe that there's something "cult-like" about them, and deciding never to come back.
What do you mean "who cares" about whether you might be humiliating someone, who may be in slight violation of traditional standards that are not known to them, in good faith ... where you would make no distinction between someonew who's trying to enter wearing a two-piece bikini and a woman who might have her top a couple inches lower than the typical cutoff.
So you're going to have a man stand there and put the two fingers against the neck of any woman who enters with a borderline-low cut, just to make sure.
"who cares ... Period" ... typifies this crappy attitude
We all should care. We can accomplish the same thing without having a woman subjected to Stubborn standing by the door ogling her and then putting two fingers up to her neck to see if she's in violation and then humiliating her by telling her to get out if she's a half inch past due.
This is borderline nuts.
You have an older lady in the back, not a male usher, who's delegated by the priest, and who's given instructions about what would require a gentle correction and would would require being barred from entering the main church (undoubtedly two different standards), and someone who does "care" and doesn't make someone run the other way and never look at another Trad chapel ever again after being humiliated by someone who doesn't "care".