Well yes. If you believe both transgender people and people with autogynephila exist at the same time, then a trans woman who masturbates to pictures of themselves is just a woman masturbating to pictures of themselves and likely just an odd thing people do regardless of whether they are trans or not. The trans woman is not being turned on by the fact they're presenting as a woman, they're likely getting the same satisfaction the cis woman is getting from doing it. No cis woman is looking at themselves and thinking "I look so much like a woman today" and getting off over it, they're obviously getting something else out of it. I assumed we were talking about photos, but it could be that they're getting sexual satisfaction by watching themselves masturbate in the mirror, which may just add some extra sensory gratification to the act for them, which is far more likely and has nothing to do with sex or gender. Someone with autogynephila doing this is being sexually stimulated directly from the fact they are dressed as the opposite gender/imagining themselves as the opposite gender.

But none of this thoroughly debunks autogynephila.

Thanks for the convo anyway, have a good day!