It stated in this weeks RL paper that clubs under SL would not have to test all their players, only any showing signs of symptoms. So that solves that cost issue. If a player ends up testing positive, I am not sure what that would then mean.
As for using wembley i think they are contracted too so may as well.
The costs of the new SL organisation is disgusting. Circa £1m of costs that didnt exist before, are duplicating work already done by the RFL and for no additional income in to the game.