They don't exclude the kero ones at least, the LPG ones would be excluded, but getting them to pass the noise test would be a challenge.

Rubber power would be legal, but would you have to weigh the plane with or without the rubber? On that note, just to push the costs up a bit more maybe they could restrict the maximum battery pack weight to x% of the airframe like they do with rubber motors in some classes.

Just imagine a multi thousand dollar F3A ship exploding when a rubber motor of that size lets go. Titanium winding stooges would be mandatory...