I'm making the guess that it is not possible in the game engine to be a monster and a wall at the same time. So that suggestion somehow misses the point of them being turned into walls, doesn't it? Not to say I don't like it, I only think this is a 180° turn instead of an addition.
Pushable statues that aren't walls and that drop gold are probably more beneficial to the player than straight-up walls with gold underneath. Harder to block yourself in, and you could set up PISORF shenanigans. So it could be a minor buff to IMAWAL, which would be nice. Might need a new name though.