I have no clue, though I would not be surprised that it came down from the BoT.
The University of Alabama System has three schools: UA, UAB(irmingham), and UAH(untsville). The System Board of Trustees sees them as essentially being one large school, with UA as the state's flagship university. UAB has the system's (fantastic) medical school. UAH has a very well regarded engineering school, especially it's aerospace program. UA is the system's liberal arts college, but also has an excellent law school and is sinking money left and right into its STEM programs. The thinking with some (apparently, at least a majority) of the BoT members is that if these schools are all just cogs in the same UA machinery, then why does there need to be a duplication of things such as athletic departments / teams? UAB isn't the first school in the system to get fucked this way. The BoT tried to kill UAH hockey a few years ago, too. Thankfully, that also failed.
However, problems arise because the two satellite schools just don't see themselves this way. They look at themselves as wholly independent universities that just happen to be part of a larger system. They see themselves as equals to UA in every way. Except they're not. And I don't mean to disparage them, only to say that their interests are not equally represented in either the state legislature or on the BoT. UAB has tried to gain its independence in the past. Hell, a
bill has recently been proposed to sever them apart. It's not going to happen because UAB has no leverage or power in the state, and the UA System BoT has no desire, much less a reason, to split the satellite schools off on their own. The Bot will never, ever let UAB go as long as UAB has the medical school.