Why do we give mentally ill people like this a platform? It's not acceptable to pass this off as okay...

You do not know if it is incorrect or not.
If it is a woman, that wants to be a man, then 'trans woman' is correct. This is the only correct use of 'trans'.

Do not allow trannies to set the narrative by accepting their use of words. If you do, you already lost the discussion before it starts.

If we're talking about biology then they are incorrect.