Trevor Phillips and another soundly GC male, Dave Aaronovitch, are out of the old, solid, feet-on-the-ground stable of '70's class-based Left politics that is not falling for this woke identity nonsense.
Tatchell was a respected mover-and-shaker of "gay lib" at that time. My guess is that Phillips, and others of his ilk, have been so busy with their own campaigns that they were/are not as aware as they might, or should, have been of the murky water flowing around Tatchell.
Tatchell is good on free speech but that is part of the general "freedoms" agenda that is problematic when it comes to "freedoms" for children. I think there is a bit of a blind spot with these old lefties when it comes to Tatchell that it is a bit like the issue with GC feminists and the GC position of the "religious right".
Aaronovitch is much more clued-up on GC issues - worth a follow on Twitter - but I've not been stalking him so I don't know how much better than Phillips he is on understanding the problems with Tatchell.
If Phillips can get his head properly around the facts, rather than just generally heading in the right direction, his will be a powerful voice for sanity!