IMO if someone cant commit to paly then , its time to move on. As long as several attempts have been made to contact such player. You being the commish/ chairman have a responsibilty , as well we the players do to monitor the forums and stay up on top of pending matches.
Perhaps you could ask the last player that requested to play and did not get in, to play as as subsitute. I got eliminated in the first round, but lolok forward to more tourneys.
nh1977