Is it not ok to be frustrated at a troll who intentionally feeds a lane?

I mean I had a last pick in normal draft who didn't want to support. So instead he went ap shaco. Because of that pick bottom lane spiraled WAYYYY out of controle with sivir being 10-1 by 15 minutes in. I got a little bit frustrated and asked for him to be reported and my team blames ME for us losing. I even get reported for it and the shaco gets no reprocussions. I played lulu top and didn't feed, won my lane, AND also didn't steal any kills and set up teammates for it but I get the warning for verbal abuse? I didn't even say anything abusive just that the shaco was screwing us over since he didn't get his way in champion selection. Why is this allowed to happen?