Why are you assuming that was his attentions? Perhaps he just struck up a conversation with her and he wanted to keep talking to her so he got her another drink. Or maybe he was using that drink as a conversation started which is why he didn't realize how drunk she actually was. Not all guys are horrible pigs out to get laid or take advantage of you.

The justification is that he tried to get a drunk girl even more drunk. That is clearly taking advantage and many people agree that that is rape or close enough to it to be completely wrong.

A guy (or girl, let's not be gender specific here) who buys an already drunk person another drink is trying to get them more drunk. Usually this is in order to sexually take advantage of their impaired state and judgement--which is rape. Drunk people can't give consent, there as it's rape. And of course there are levels to this sort of thing--if you have a long standing sexual relationship and like to drink and sex, that's fine. That's completely different from meeting someone in the bar and preying on their impaired state in order to have sex with them.

Her comment follows in line with the comments above her, which she responded to even. Her comment would have made more sense as a reply instead of an individual post but there you have it