This was already explained to you earlier in the thread. “Male” and “female” are, biologically speaking, not distinct and mutually exclusive categories in humans. This is the case naturally, and the terms become even less useful once you account for those who modify parts of their biology, whether by surgery or by artificially triggering natural biological processes, to bring those parts into congruence with other parts of their biology.

“Biological male” is a slur. It has no basis in science. It’s a term coined by bigots to misgender trans people with sciencey-sounding words so their abuse looks reasonable at a glance, in much the same way that proponents of Scientific Racism use pseudoscience in an attempt to legitimize white supremacy.

Also the term is referring to their original status pre-hormonal or other gender affirming care so no.

We already have a far less problematic set of terms for that: Assigned Male at Birth (AMAB) and Assigned Female at Birth (AFAB). “Biological male” is a scientifically misleading phrase that bigots invented to slander trans people and it should not be used by anyone.

The same reason anyone would be: because their current body doesn’t match their gender identity and they want to change that. This person just happened to start inside the same arbitrary social category as their destination.