elsewhere, AD's go hire somebody and that's it. here, the AD choosing a guy is just the start of a long process of administrative and bureaucratic junk. BYU admin needs to do all kinds of vetting- is the guy temple worthy, will he follow the Honor Code, all that crap.
then whatever General Authority(ies) need to interview the guy. And BYU basketball is not their primary focus, they'll get to it quickly, but not nearly as quickly as we would like. I frankly doubt any of them are going to nix a candidate, but getting the interview done still will take some time.