You can only interview for coaching jobs at certain periods of time in the NFL. So he didn't "wait so late" -- it is why it was so late they announced it.
And I'm not sure how it hurt recruiting? We actually picked up two big time recruits late -- in Keon Sabb from Clemson and Derrick Moore from Oklahoma -- they were two of the highest ranked recruits in the class. So recruiting wasn't hurt at all, which actually shocked me. Now losing coordinators is what hurts us and I don't blame McDonald or Gattis for leaving. I'd have done the same thing. Why commit to a coach who won't commit to you?
And I can't imagine any college saying -- no, you can't interview at the highest level in the coaching profession. If the NFL wants you, they are going to bring you in. Now many coaches have no interest at all at coaching in the NFL, as it is light years more difficult than college, while some prefer the NFL as you don't have to do as much travelling around the country recruiting. So I don't blame UM for letting him interview, but Harbaugh has lost all trust from the fan base -- personally i think it is only a matter of time before he leaves for the NFL, so why would a player or coach want to commit to him or the program?