the argument is that AGP is technically a paraphilia and not an orientation

Yes, but Blanchard's typology makes sense in this context when you realize that the paraphilia becomes all-consuming to the point of eclipsing the primary orientation - i.e. why we see so many extreme, hyper-performative examples of heterosexual father-of-five, longtime-married AGPs troon out in cartoonish fashion and end up engaging in sex acts with men to validate the "identity".

Of course lesbians are the ultimate validation, but a large proportion of the worst-affected seem to be willing to take whatever sexually-based validation they can get, so long as they are in the conceptual role of "woman". These males are not suddenly bisexual; on the contrary, this would seem to indicate the extreme levels to which many of them have objectified the conceptual (and real-world) "woman", that they in turn act out this performative role assumption.