The 'excellent study' would be the puberty blocker trial and its sister studies, however that seems to be going nowhere.
The NHS Tavistock study wouldn't be excellent, even if people weren't now trying to sabotage it by withdrawing consent.
The pictured text is the rationale for not doing it in the first place, and it wasn't about concealing the truth. It's because their data is shit.
The Tavistock did not record cognition, childhood adverse experiences or neurodiversity. How can you compare outcomes in any sort of valid way if you haven't registered starting points?