So, if it is a big deal, why are you splitting hairs about it?
If you knew someone who behaved like this, would you be ok with it? If you were held down and threatened at a party, would you be ok with it?
That’s the thing here. This is a big deal regardless of whether or not this meets someone’s definition of rape, as you yourself have stated.
Otherwise, what you are essentially saying here is “Someone who behaves this way doesn’t deserve scrutiny or for this sort of behaviour to be used to judge their character, because the behaviour was not abhorrent enough to be unacceptable to me”.