The justification is not the problem, it's the targets. People will give that excuse even when it's a blatant lie.
As far as I am aware, the discussion of 'fake geek girls' has mostly come from MRA-types that spend most of their time failing to see women as people. So any particular instance of 'fake geek girl' is almost certainly the commenter being an ass and wrong. But, again, as far as I am aware, there are no large groups going around being 'anti-hipster' in situations where it doesn't fit. So instances of being 'anti-hipster' are often accurate.
As far as I am aware, the discussion of 'fake geek girls' has mostly come from MRA-types that spend most of their time failing to see women as people. So any particular instance of 'fake geek girl' is almost certainly the commenter being an ass and wrong. But, again, as far as I am aware, there are no large groups going around being 'anti-hipster' in situations where it doesn't fit. So instances of being 'anti-hipster' are often accurate.