This is so misleading. It's not limited to time off for surgery, it's anything to do with reassignment, which the individual gets to decide so covers things like :
Laser hair removal
Make up lessons
Personal stylist appointments
Voice training
Tattoos
As well as all appointments.
In contrast my friend with PCOS who needed vaginal surgery to relieve intense pain and regular sick leave for symptoms very quickly ran out of allowed time. She also needed laser hair removal and was told that was cosmetic and so take annual leave.
We just want it to be fair. Trans people get the same sickness policy as the rest of us.