It can be really hard, almost impossibly hard, to make decisions when you're suddenly confronted with a situation that breaks your understanding of a person you trust (especially a person who has power over you, and especially a situation that seriously violates social norms) - at that moment, you're intensely confused, with a big "WTF" blaring in your head, your brain is flooding with panic and adrenaline...it's not hard to understand freezing up and just making the small efforts that are all you can manage, while hoping that it won't escalate (even while it keeps escalating).
It would be great for everyone to be able to bypass that shocked paralysis and immediately push away their attackers, but it's not realistic.
In the US, at least, consenting adults are free to do what they like within reasonable limits, of course with a concession for obscenity while in public. There's nothing particularly obscene about doing a body shot in good company. Had it occurred to you that some might find it fun?
Two things about your "culture":
1. Why does your culture seek to prescribe sexuality in such a seemingly overbearing way?
2. Has your culture not yet moved beyond slut-shaming, which is irrational and harmful for all parties involved?
It would be great for everyone to be able to bypass that shocked paralysis and immediately push away their attackers, but it's not realistic.