I think the spirit of the rule is fine. And the NFL doesn't dictate who you must hire. It simply gives minority coaches opportunity to be considered.
But there's no perfect solution. If a team wants a specific coach who they know, it is insulting to minorities to go through the charade of an interview when they decision has already been made.
On the other hand - as the rule is intended - when a team is not sure of who they want, and interviews several candidates, it offers opportunity to the minority coach. That is a good thing.
Mike Tomlin was interviewed by the Steelers when they already had a pretty good idea who they wanted. (I forget who that was, unfortunately.) But Tomlin impressed them so much, he got the job.
But, yes, in cases where a team knows a coach and wants that one specific guy, it seems silly, or even insulting. Especially in this case, where they are rehiring a former coach.
Switching sports here, but....Imagine Steinbrenner having to hold a mock interview before rehiring Billy Martin 5 times!