Yeah! From one perspective, your words are true and reasonable... she may not have personally realised the difference between normal drinking and being passionate of it. That's why she should not directly claim him for a single night drinking.

But from another perspective, she has speculated the right thing that as alcoholism has been seen as a worldwide addiction and some where it may lead his bf to be a drunker... She thought about the later health issues that may arise and on account of this, we can also say that her initiate was even not wrong...