All you arguments do make logical sense.
Luckily, the police, firemen, and many others ignored just that kind of logic on 9-11. Many are alive today because they did.
Rescuing the folks from that disaster was not the same thing. First, the folks in the tower didn't set up the disaster. Second, it was not at all clear that the building would come down as it did. Third, the rescuers did not have the opportunity to know by observation and examination, that there was nothing they could do to save the victim.
Police and firemen are trained for rescue and are equipped with the rescue gear.
And I find it interesting that one of the first things they do at the scene of an emergency is to keep the untrained passerby from trying to perform some John Wayne rescue operation. Stunts like that are a good way to get more people killed.
If these people weren't trained and did not have the proper equipment, they probably made the correct decision.