The interpretation of 'passing through check' is usually based on the King move not being atomic, but having to be broken down into a sequence of intermediate positions. Where each of the intermediate positions then would also have to be legal as a final position. (Note that is an independent issue from not being allowed to move out of check, which doesn't need any intermediate position, but puts a condition on the postion after a turn pass.)
Metamachy is unusual in this respect, as legality of the initial King move also depends 'attacks' on squares that the King can never visit as an intermediate step, because these squares are already occupied by another piece.
The interpretation of 'passing through check' is usually based on the King move not being atomic, but having to be broken down into a sequence of intermediate positions. Where each of the intermediate positions then would also have to be legal as a final position. (Note that is an independent issue from not being allowed to move out of check, which doesn't need any intermediate position, but puts a condition on the postion after a turn pass.)
Metamachy is unusual in this respect, as legality of the initial King move also depends 'attacks' on squares that the King can never visit as an intermediate step, because these squares are already occupied by another piece.