The cover for the airbox on this Honda generator hinges open to the left, but the frame rail is directly in front. The airbox is also bolted to the engine from inside (behind the filter).
I've throughly looked over this and there is no way to open that airbox unless you unbolt the engine from the frame, or perhaps modify the lid hinges with a saw so it doesn't have to swing as far to come off.
No; it bolts directly to the carburetor. If it was flipped upside down (vs the current orientation) it would be running into the fuel tank/upper frame rail. Then it would hinge open in the other direction, but still hit the frame and be stuck shut.