There are 21 blanks which I assume are being held for top players who haven't responded yet.
In that same Loose Pool Podcast Emily said something to the effect of that as soon as they realized they were going to sell out all the spots within minutes, that they made the call to hold back some of the spots for Americans because they had gone on sale at a less than ideal time of the day for the Americans and with the implication being that nobody was expecting that they would be selling out quickly like that. She did not say how they would determine who the remaining spots would go to, nor did it seem that they knew yet, they just held some back as soon as they realized they were going to book all up in minutes at a less than ideal time of the day for Americans to be on booking spots and were going to figure the rest out later. The whole thing was unexpected for them and she either said or alluded to them not even being confident they would be able to sell out all the player spots for the event, and the possibility of that happening in minutes was never even conceived of.
She also clearly insinuated that at some future point players better be prepared to get their spot the moment they go on sale regardless of when it is, that responsible people have to set alarms when it is time to either get up or get reminded to get things done, etc.
In the future this is how I think Matchroom should handle putting the player spots on sale for open events. For the simplicity of discussion I will use an example where it is an open tournament with 256 player spots. Publicize the date and time the spots will be released for sale, and that they will be accepting ALL fully paid submissions for a period of 48 hours but that they are still considered tentative and not yet confirmed/guaranteed at that point subject to final approval. At exactly the 48 hour mark, if they still have spots left, then everybody that is already paid is to be confirmed as being in, and it is first come first serve for the rest of the spots until they ultimately sell out. But if at the 48 hour mark they have more than 256 paid sign ups, then take the top 256 players by FargoRate and refund the rest and let them know they did not make the cut to get in but that they are on the waiting list which will also be continuously ordered by highest Fargo rating and anybody can get added to the waiting list at any time
Once Matchroom has their ranking points list fully established with enough data, they can use the Matchroom points list rather than the Fargo ratings to determine the top 256 to get in, or they can use some combination of both at that point, but the point is that when they sell out right away/way in advance they should be shooting for trying to get the top 256 players (or however many) rather than just the first 256 players who signed up. The method I outlined above would be completely fair to all, would not cause any undue inconvenience, and would also be the most beneficial to the sport, to Matchroom, to the fans, and to everybody else.