"you need to rebut her premises, not dismiss her because of perceived bias. The woman is a PhD biologist. What are your qualifications other than your obvious transphobia and allegiance to dubious pseudoscience?"
You can't cite a clearly biased article as fact. I would think that everyone learns that shit in high school.
The entire premise of Serano's argument (if taken at face value) is that that the AGP theory is false because trans people, their doctors, and their academic allies all say so. However, this is by no means a compelling argument against the existence of AGP and it's role in transgenderism. All of these people are biased in favor of the transgender side of the argument, and thus will always say what they said. This renders the argument invalid.
In a discussion like this, people don't need credentials as they are voicing their opinions. Opinions aren't meant to be taken as fact, yet they can be criticized based on how logical they are. I was criticizing your argument by noting that the "reliable source" you cited wasn't reliable at all. It is also important to note that experts can get things wrong. Just because Serano had a PhD doesn't mean that what he said was true.
TL;DR: Check your sources for bias next time