Yan Fei's tactic of depleting energy wasn't omnipotent; it only worked in a large city like Los Angeles. Elsewhere, the mysterious aircraft wouldn't have hesitated to attack the drones first. Even if this resulted in some building damage, it would have been worth it to destroy the drones from Dream Island.
Yan Fei didn't actually aim to demolish these buildings; his real purpose was to drain the energy of the mysterious aircraft. That's why he only launched ten AGM-114 Anti-Tank Missiles at a time, afraid that too many missiles would overwhelm the aircraft's interception abilities and actually destroy the buildings below. Then, the mysterious aircraft would lash out in fury, ignoring the missiles launched by Yan Fei and relentlessly attacking the drones instead.
