A ruling has been requested.
Since I am away I will not have time for full due process, so here is the ruling:
It is not each picking player's responsibility to verify the validity of all prior picks. Our own version of Caveat emptor - let the buyer (picker in this case) beware that their pick must be a valid pick or they risk getting skipped a few picks until they can repick. We will all work in good faith to identify invalid picks as early as possible. This is also consistent with our prior practice.
If we were in round 1-10 I might consider the other approach but given all factors Gordie must now repick from the available player pool. As a courtesy we will pause the draft for at least 8 hours to allow him to not fall any further behind. Or of course we can resume as soon as he picks.
Either that or we have a Kirk-Spock fight to the death like they did on Vulcan when Spock was in his mating mode.