No it says the rifle must be supported by the hand.
Your rifle isn't supported by the hand. It's supported by the leg underneath it. If you apply downward pressure there is no change in your position. If the hand was unsupported your position would change under downward pressure.
There's no 'in theory', if buts or ands. The position is clearly in the pictorial guidance as to be considered illegal by a marshal. The pictures are there for clear indicication of how to understand the words.
BFTA/NSRA County Coach
CSFTA Chairman/BFTA Rep