I think Rome should be getting heat too on that play. It looked like Rome was running a clear out like you said but he stops running too which freed up the Houston defender to break so hard towards the ball. If Rome is running all out that might occupy the safety. I see exactly what Caleb was seeing when he made the throw. The question is what route was DJ Moore supposed to be running and does their playbook call for adlibbing. That type of chemistry takes time to build and if it's not something they are used to doing, if that wasn't Moore's route then it was a dumb throw by Caleb.
A large number of Mahomes great plays was him just reading the D and throwing to an open spot in the field knowing that Tyreek or Kelce would see the same thing so they'd improvise. I was watching a lot of Mahomes Tyreek games recently and his deep ball was always inaccurate. Tyreek was just an amazing ball tracker that made his deep ball look way better than it really was.
Right Rome wasn't running hard as well, it really seemed like none of them expected a deep shot on 2nd down when the Bears were trying to take safe yardage to get in FG range. I personally think Caleb was feeling himself and went for a killshot when everybody else expected him to play it safe. They probably dont have the chemistry yet to pull something off like that on the fly