Because the function is to place oversight of trans people in sport under political control (of Republicans).
The commission's members are appointed by varied elements of the Utah government all of whom are solidly Republican. So Republicans appoint commission members guaranteed to come out with the right opinions, whilst also keeping themselves at a safe remove from controversy because the commission is "independent". The commission members being immune from legal suits leaves them more free to rule as they please.
Just to be clear here, I wanted Tstorm to answer it. Because they seem to be under some illusion of what this process is.Which they then say isn't good enough and reject the student. Or give them the run around and demand more and more invasive tests, which never quite hit the standard they're looking for.
The important thing to remember is that they don't actually care about fairness: the GOP would shutter girls sports in a heartbeat to save a dollar if it weren't for Title 9