I think people seriously misunderstand the actual power and destructive mechanisms of nuclear weapons.
This was a 2 kiloton air burst from over 3 miles away. 2kt is less than 1/5 the yield of the Hiroshima bomb (which was 12-15 kilotons, depending on which reading you believe), and the destructive blast radius at Hiroshima was only about 1 mile.
Airbursts don't generate any "fallout", and at that altitude there was very likely no "mach stem" to create the really big destructive overpressure wave.
This was a 2 kiloton air burst from over 3 miles away. 2kt is less than 1/5 the yield of the Hiroshima bomb (which was 12-15 kilotons, depending on which reading you believe), and the destructive blast radius at Hiroshima was only about 1 mile.
Airbursts don't generate any "fallout", and at that altitude there was very likely no "mach stem" to create the really big destructive overpressure wave.