I have not read the series so I can't really comment on most of it since I feel like I'm missing a lot of context here. There are two points that stand out in the article, though.

The first being that apparently, if I understood it correctly, it's somehow weird that an actually disabled man (who never chose to be disabled) might be offended by the fact that someone else actively wants to be disabled? Sure, an actual disorder is involved and that deserves empathy, but the visceral and (more importantly) realistic reaction of Strike deserves that same empathy.

Secondly, it's this:

"If the root of Rowling’s books is the constant miracle of overcoming considerable odds with love and courage to negotiate hatred," explains writer and transgender woman Charlotte Clymer, "trans people, who leave our homes every day into a world full of discrimination and violence against our bodies and souls, are the closest thing this world has to magic."

Rowling is being accused of not being inclusive enough, but how is this inclusive? For lots of people this is a reality, but screw them, it's only trans people that are "the closest to magic".