Considering that it was an honest mistake by Impo, still I think the game must stand.
If Impo would accidentally surrender in game, that would still count as dt's win. Given the situation at the end, the drill does count as an end game to me. However if I were in avi's position, I'd ask Impo to teleport back up.
I'll ask other mods on this, if they had the same opinion as me, I'll mark this as solved.