I don't doubt KS had/has a plan, but it's crazy talk to say he can't begin the process until dismissing the prior employee. Of course you can talk BEFORE firing them. That's like quitting a job before you start looking for another one. Granted, a decent but not perfect parallel... but who does that? As one of a possible gazillion examples of looking before things are official: Scott Frost leaves UCF on Saturday and UCF hires a new head coach on Tuesday! Three days later! There's no way UCF (a) didn't know SF was leaving and (b) they didn't start reaching out before Sunday. Same thing here. There's no reason KS couldn't have been reaching out prior to pulling the trigger on Ty's dismissal. Frankly, I suspect he did so extensively. He's dumb if he didn't. I don't think he's dumb.
I would guess the hold up is much more along the lines of BYU being slow to approve hiring decisions. That's the proven MO around here.