A bit unclear indeed. But to be honest, for me and my opponent, it's never been an issue. Me playing Squats, I only have the Overlord, that is a flier/floater. The base movement of the Overlord is only 15cm so I have honestly never been able to put my bombs to use. Putting the overlord on charge for a bit more movement, sacrificing all those juicy die/cannons has never really been an option

The flier rules in NEG states that a charge order doesn't increase the base movement, it just makes it possible for the flier to engage other fliers in CC. My ork fellow that has one model of the Blasta Bommas, and that one has an insane movement of 100cm, so it's just always felt like a waste putting it on charge. Advance is basically the only useful move in our battles.
I would probably allow it to drop bombs when on charge since the attack is immediately resolved. But that might be because I know in our battles, it basically never happens.
For us playing only Squats vs. Orks it's honestly never been an issue. The only floater (I don't count the observation balloon here

) I have, playing Squats, has such a low movement (15cm) that I have never had the chance to use the bombs it has. Putting it on charge and sacrificing all those juicy cannons has never been an option for me

My ork fellow player has on one occasion used the Blasta Bomma, and that flier has an insane movement of 100cm, again making