I think Dave is just completely a spoof caller rather than a trans person 'making a point' or a trans spoof caller, although I realise there's not much distinction between the three.
I think this because he says 'You can call me what you like'. This is not usually acceptable to people who follow the ideology that humans can change sex. They're normally very keen to control other people's speech and even want to control what others think of them.
I would put Dave in the category of a bloke 'having a laaarf' by telling an outspoken woman to drop dead, but in a roundabout way to make it seem more reasonable, perhaps to himself. As such he may not even care how this reflects on the 'trans community', although there are plenty of other examples of individuals who are so completely narcissistic that they don't realise the damage they're doing to their own argument by making insane threats against women. KJK really knows how to make the most of that situation!