Because nobody expects such threads there and most wouldn't post there in the same way as they post here.
The language of the OP was very goady, nothing to do with support. Much more 'spiky' than this version. Lots of cis this and offensive that!
It's a support space for parents with trans kids. Not an FWR free for all.
Plus I don't know why I saw it, I have all of the children threads hidden. There is some speculation it was moved there after we started posting on it.