If a player was truly homesick and there are family problems, then if Miami said no, they'd just as easily go to FIU, who would be happy to take them. If they live in Northern Broward, then FAU would be happy to take them. If they don't end up at FIU or FAU then you know its some fugazi nonsense and its a playing time issue and ultimately that wasn't a player we want/need at Miami anyway.
I do think a blanket policy/doctrine is silly, but these transfer-backs don't often work anyway. There are a few, sure...but most aren't worth the trouble.