'they' is gender neutral, but it is plural, not signular.
english doesn't have a gender neutral singular pronoun, historicly 'him' has been used both for males, and for the generic pronoun.
in my opinion, getting to the point where you are arguing about what pronoun people use is over the line awaoy from sexual harrasment and sexism, and actually weakens your case.
this thread started out dealing with really important things (people sending death threats because a person is female), and here has devolved to "don't use 'him' to refer to someone that you don't know the gender of". can you see why arguing the latter cheapens the former?