4. Harbaugh is well-connected and has a relationship with Kevin Warren
First, let's establish the elephant in the room. Back in 2020, Warren was of course the Big Ten commissioner. He wanted to shut the season down, while Harbaugh wanted to play through the pandemic. That certainly could have resulted in some animosity between the two of them.
There are reports in the media that suggest the two of them "don't like each other," as evidenced below.
At the same time, Warren is a professional. Having seen the work Harbaugh has done, firsthand, he cannot deny the fact that this is a great fit for the Bears. Warren and Harbaugh may have had their differences, but I think them both being men who care about the game, and care about winning, would trump any previous situation.
Harbaugh is also well-connected around the league and in the college ranks. Because of his experience and his résumé, he could likely bring in whomever he wanted to be on his staff, including a top offensive coordinator.
This wouldn't be like hiring a first-time head coach who looks to be one of the next, great offensive minds in the game. Sure, that might be a good route to take. But, Harbaugh is well-established and well-connected. He's a no-brainer for this Bears team.