How about if:
Player 1 uses this to transfer troop losses from Ship A to Ship B.
Player 2 uses the same ability to transfer losses from Ship B to Ship A.
Re-wording it to make the ship that losses are transferred to have to be friendly would avoid this.
Also, if the ship having losses transferred to has yours and enemy troops on board, are losses shared? randomised? or taken from the owners troops?
Another thought, if the ship having losses transferred to it has no troops left, can the losses still be transferred to it, or does the original ship now have to take them?