It's difficult to imagine the Taliban being stupid enough to leave their key people behind to die in place, rather than leaving as 'Refugees' days in advance, only to return (With our help) later to assassinate the Afghan government gusy we are trying to install.
There is actually more to it than minimizing collateral damage, it is also a way of demonstrating that they can't face us in a stand-up fight. This point is completely lost on the Afghans it is supposed to impress, of course, since they have been thieves and dry-gulchers of renown throughout their recorded history, so it's a stupid point to try to make.