Or 4) people who have looked carefully at the controversy and concluded that Rowling is not actually transphobic. I have read most of what she has written on this topic, and I see only two things she believes which make people think she is transphobic
1) she thinks that no one should be allowed to be treated as a woman just because they say that they are a woman. She is not worried about what trans people will do if anyone can identify as a woman. she is worried that some cis men will pretend to be trans and thus be able to get into women's spaces and assault them.
2) She is afraid that the current conversation about Transpeople will inspire many CIS young people to think they are Trans, and thus get surgery that they will later regret.
As far as I can tell, she is wrong about both of these things. But believing these things does not make her transphobic. That's because these are not beliefs about trans people at all. They are beliefs about people who are either pretending to be trans or mistakenly believe that they are trans. As far as I know she has never said anything negative about transpeople in general. (although I'm sure she has made some nasty remarks about the particular transpeople who have verbally abused her.)
There are real Transphobes out there. Germaine Greer believes that all Transwomen are men who are culturally appropriating femininity. She compares them to Blackface Minstrels, who are wearing femininity like a costume. That's Transphobia.