Hmmm... I can immediately think of a reason this won't work.

If I create a constraint that says "Bishops are only capable of moving 4 squares maximum", the set of valid moves you are passing into Stockfish only affects the initial move.

But as soon as it starts to build the minimax-equivalent search tree, it's no longer enforcing that constraint.

To make this work, you’d have to get Stockfish to continuously enforce the “bishop move” rule at every ply during its search.

Caveat - unless this is something you are enforcing in searchmoves? I don't have a lot of experience with in-depth usage of Stockfish.

Alternatively, you could look into Fairy-Stockfish, which allows you to define rule variants.

https://fairy-stockfish.github.io