Ok well -
On the one hand this is a philosophical argument about the semantic meaning of the word 'knowing'.
On the other hand you saying 'Dr Upton can't know something that isn't true' requires us to agree what is 'true'.
The problem is that we don't.
Whatever words we use - the issue here is that people keep making the statement:
"Dr Upton knows he is male" - a claim about Dr Upton's subjective 'knowing' of self.
This claim is empirically false.
Dr Upton's subjective 'knowing' of self tells her that she is female.
This is the reality of her cognitive experience - despite the fact that she was registered male at birth and her body has physical characteristics that are usually associated with being male.
This is what it is to be a trans woman.
You may say that Dr Upton's cognitive experience of self is 'wrong', 'false', 'deluded', 'stupid', 'mentally ill', etc. I disagree that those labels have any utility. But regardless, the point is that it is what it is. This is the reality of what it is to be trans.