Imo, if your oponent will agree with this trick u can use this tactic, why not? So many option there(turn order, positions, ur sd wpn, ur wpns, ur and oponents HP's), sometimes it will be be really useful to surrenger, sometimes not, depended of situation and scheme what u play.
But, before surrenger, ask ur oponent, and dont do it if he didnt answer - by default it should be not allowed.
If your partner in clanner need to go is other quastion, game should be replayed or continue if oponent agreed 2vs1
So. All depend how long our gods will change page with rules hehe..