It may be that you're awkward socially or something which is causing you to incorrectly assess the situation, relying on hard and fast rules in a dynamic situation and thus coming off as either virtue signalling and/or prudish.
It's much more common for people to kiss in a lot of places outside the US, even men. It's a common behaviour in celebration. This guy may have taken advantage of the situation sure, but that does not equate assault or indeed necessarily sexual.
Regarding your assertion that he grabbed her breast, he essentially hugged her and his hand landed on a breast, approximately 40% of the area of her upper torso. There was no squeeze, and this is telling, men with experience of women are not interested in touching the jacket of a attractive women. I've worked in clubs as a doorman for decades and the sense of feel is the point of the move, that's what I've observed in 99% of predatory moves.
He likely intended just to kiss her on the cheek and I don't see that as a sexual assault.
Regarding your talk about my daughter, if it were to happen to her when she's no longer a toddler and in her womanhood, I would hope that she could assert her displeasure should the event occasion her dissatisfaction. I'd certainly not want her to be a pussy about it or cry to some white knight to baluster her ego.