It may be also that the opponent left the game as soon as the round started, maybe they saw they were in a loosing position? Or since the outcome was already decided, round may be very long, they could just quit the game (not concede) to gain time without loosing the round. In that case, I do not think emoting would work since emotes go directly from player to player, not through the server. So no more connected opponent, no emote.
See the graph in this posts for the various connections between your computer and servers / opponent computer: