So?
Just let him AFK farm for 10 minutes and he'll start twoshotting anyone.
Give him 10-15 minutes to bake and he will be 10/9 before you know it because kappa
Ban him.
Even if someone on your team wants to play him just ban him out. You know he's gonna go 1/6 90% of the time anyway.
Might as well force the Yasuo onto something else that can assist the team.
Then you realize if he was on the other team he would probably be 9/0, Yasuo only ever seems to operate in the extremes.
Yasuo is the new Yorick. Yorick is the new Yasuo.