I'd wager a LOT of money that the Falcons' QB situation going into next season will be much more appealing than their QB situation this season. They'll either trade for Fields, or sign Cousins, or stay at #8 and draft someone like Penix, or trade halfway up and try to draft Daniels, or trade all the way up and draft Williams or Maye. Their worst-case scenario probably is signing Wilson or Mayfield. They will NOT have the Ridder/Heinecke platoon in place. And because any new coach would presumably have plenty of input into which of these scenarios works best for him, that cannot be the only reason Belichick would stay away from the ATL.
I'm personally torn on whether I want Belichick in Atlanta, for numerous reasons. (On the whole I'm in favor of it, assuming he's fully motivated to prove everyone wrong and show that he's still got it.) I also think he'd be silly not to wait to see what happens to Philadelphia and Dallas in the playoffs before signing on the dotted line; those are the prize jobs that are clearly better than Atlanta. I think I'd rather have Harbaugh than Belichick if Harbaugh is interested, as I think Harbaugh is more of a sure-fire bet to succeed *and* might also be around for more than 3-4 years. But really, hiring coaches is almost as much of a crapshoot as drafting quarterbacks, so who the heck knows?