DIRT bike racers should have an explanation for this one as they inverted there shocks years ago in the front.....
With rc clearances would be hard to maintain in some cars if you inverted the shock. The lower arm mounts on my B4 buggy would not accept the flip.
Not sure if air in the shock would be any worse upright or inverted, once the shock has been pumped a few times any air in the oil has be mixed.
good question not stupid at all