The same reason Deshaun never made the active roster this season and didn't get put on the exempt list... Orders from the top. My guess is the NFL is heavily against one of its teams hiring a coaching candidate who effectively is trying to tear down the league's initiative to hire underrepresented coaches during a time where, socially, this is a highly promoted topic. The NFL wouldn't directly punish you, likely, but the league and owner's group could make your life more difficult for the foreseeable future.
The Deshaun/Miami thing is starting to add up. I can't remember the exact quote, but Mahomes signed that 10-year extension which gave the Chiefs a ton of flexibility to continue to build around him. Watson said something like "it's a different situation for me" and seemed to not really want to extend with the Texans.
Fast forward a month or so and BoB is the GM, BoB is inept and making terrible decisions, etc., Watson now is content to sign a "long term" contract with the Texans that is guaranteed for a lot of money and allows him to control where he can be traded. 5 months later he begins to demand to be traded to only Miami because he wasn't "consulted" on his vacation on the GM/HC hire? Now there was a franchise qb in Miami in January being entertained by Stephen Ross the same time Deshaun is posting social media in Miami?
I know the media is saying it's Brady, but I have a hard time NOT connecting these dots. I think this was Deshaun's plan all along and kudos to him for securing the bag and future. That said, if this conspiracy theory is true, he's worse for the organization than Easterby is.