FWIW on my shallow knowledge if anyone's saying that AGP is THE cause of the desire to transition that seems crude and simplistic to me. But equally, rejecting AGP as ever having any component part in a desire to transition also seems really unlikely. Why wouldn't there be an erotic component to gender identity? Or to gender transition?
Unless you are committed to the idea that a person just "is", and were born, a different gender than the one which they have been assigned in which case it becomes necessary to obliterate AGP because it relates so strongly to the act of transition rather than the magical state of being the correct gender.
Do you think AGP is a component of some people's desire to transition? Or is it never?
No I wouldn't say never, there are few absolutes when it comes to human beings. But if autogynephilia is a product of gender dysphoria, rather than the cause, then even if it is present it is not the underlying reason why someone might want to transition.
I think it's also difficult to nail down exactly what autogynephilia is. Is it solely erotic arousal at the thought of being the opposite sex, or could it also be arousal at the idea of being sexual in a body you do not feel dysphoric about - Blanchard has always struck me as woolly about this. Because if the second were a motivation to transition would that really be autogynephilic, or just a motivation to have a sex life you can enjoy because you are in a body you feel comfortable (or non-dysphoric) in?