Is it possible to report someone after the post-match lobby closes?

I was playing splitscreen with a friend and someone on the opposing team was being really rude and wasn't appreciative of the fact that we had bad lag. I wanted to report them for unsportsmanlike conduct but my friend as player 1 reported the wrong guy and we were kicked out the post-game lobby.

Normally i wouldn't be too bothered but i really felt this guy needed reporting so badly so I'm rather annoyed he got away with it. Is there no way of reporting someone at a later date? Or has it Ben revealed that this will be later implemented?