I’m going to give a longer explanation than was already given.
So, imagine yourself at a hospital. You’re about to have a minor surgery, and get knocked out. While you’re under, some nurse comes in and fucks you in the ass.
Is that rape?
Switch things up. You’re at a bar, having a good time, someone slips something in your drink. While you’re under the influence of that hit of whatever, they take you into the bathroom and fuck you in the ass, and you agreed to that, you may even like it.
Is that rape?
On a fundamental level, if someone is visibly drunk, or even olfactorily drunk (meaning your can smell the booze on them), they are in a state of mind that is the same as being drugged. It doesn’t matter if they are initiating contact, they are unable to give meaningful consent.
Now, if you want to argue we need another term instead of rape, I’m okay with that. We can call it whatever. But we have statutory rape already, which exists because we recognize that even when someone is the initiator, there are states of mind and being that simply can’t make a choice to have sex in a meaningful way. So using the term rape for violating meaningful consent is fine, even when it’s an adult, and even when they initiate.
I am also aware that there are edge cases where consenting before consuming a substance could/should count as meaningful consent. And I’m aware that there is a range of inebriation where meaningful consent is still possible. However it is nearly impossible to tell without testing what a person’s blood alcohol level is, so we’re limited. That in turn means that the standard for (at least colloquial usage) what is and isn’t inebriated rape has to be broader than it would be if we had reliable testing on the fly.
I also agree with your point that she was ignoring consent, and being an absolutely horrible person, and if she had persisted by force or coercion and he had given in, I wouldn’t accept her being drunk as a defense against any charges brought.
But there’s a fundamental inability to consent when drunk. How drunk? That’s something that would need to be addressed by medical science and then legislated. What’s the maximum BAC someone can give meaningful consent for other things? But that fact is there, that alcohol serves to break down the ability to consent, and sex without consent is considered rape, on at least a colloquial level, if not always on a legal level everywhere.