Even if the intent is not to drop boosters, as long as there's some reasonable chance boosters will be dropped (accidentally), I can see that requirement sticking around.
The energy output of a jumbo jet is four orders of magnitude less then that of a rocket. A jet engine is equivalent to a controlled fire. A rocket is equivalent to a controlled nuclear explosion.
There's almost as much energy stored in a BFR as there is in the nuclear bomb dropped on Hiroshima. This energy is released over 3 minutes.