I entirely agree and was/am hoping for 1-2 more years with him for Allen. It falls more on the developmental aspect of it for Allen is where my concern lies.
There is also a chance that he doesn't want to place his HC career prospects with Haslam as an owner, the track record of the HCs and in abilities to get hired after, Dorsey's drafting of questionable characters, etc. Not so sure he would just jump for that. With the rep he has right now he can be a bit more selective IMO