[elictronic]

He specifically says if the motors independently tilt. This is active control. The Rocket pendulum fallacy is only valid for systems requiring passive stability.

Tandem rotor helicopters exist.

[montymintypie]

Rockets also have active control via gimballing motors. Bicopters tilt their motors to control pitch and yaw, roll is still governed by motor speed.

I was arguing against the COG of the payload, not of the existence of bicopters entirely.