Transphobia, homophobia, racism, misogyny
... calling her a man either because she isn't traditionally feminine or because in their heads, testostetone is a "man's" hormone so if you produce too much, you're obviously a man. No surprise that a lot of these twats are horrifically transphobic. I've also seen people insulting her for being a lesbian and having a child with her wife because "two women can't make babies so one of them must be a man" (yes, this is an argument people use in 2019)...
Transphobia, homophobia, racism, misogyny
So yeah, the IAAC's ruling is a clear example of a white governing body trying its hardest to protect the interests of white people at the expense of people of colour while also propping up the patriarchal idea of strict gender binary.
In short: screw the IAAC, screw the people celebrating this ruling, and good luck to Semenya in fighting it