Time restraints in USMS Open Water Championship races

As an "older" female swimmer, I wondered how they come up with the time restraints in the National Championship Open Water swims. For the 10 K race, the entry form it said "the race will end two hours after the first individual finishes. All swimmers that have not completed the course at that time will be asked to retire." For the 1 mile race, the entry form stated "swimmers still on the course after the 60 min. time limit will be stopped and listed as DNF in the results." By my calculations, in the 1 mile swim you would have nearly two and one half times longer than the first swimmer to complete the race, while in the 10 K race you would have less than twice as long. I would like to see more time allowed, especially for the longer distances. I understand the push to make the day as short as possible but I feel older swimmers are disadvantaged by these restrictions. Older women, are even more disadvantaged. Perhaps more older swimmers would participate if they were not threatened with a DNF if they don't make the cut off times. Does anyone else have a concern about the time limits in our Open Water National Championship races?