I doubt the sky divers would be jumping if they had a cold. Many pax, even crew, fly when they have a slight cold. The auto cabin rate of descent can just about be survived with some nose blowing and swallowing. Sit next to a child who has not been taught this technique and watch their parents teaching them. Perhaps this was why in the olden days they used to dish out sweets at TOD. Anyway, having been in an a/c with a screaming pax who had a cold and whose head started to explode below 10,000' I've seen the result. Out of 100's of pax & crew i can be confident someone is likely to have dodgy ear tubes for whatever reason. Slowing down the ROD passing 14,000' should have no negative O2 effects on anyone.