You're absolutely correct. In my younger days, I often hiked above 14,000 feet in the Sierra Nevada Mountains of California. Breathing was a little labored, but I made it just fine.
Either way, the parachutes have a delay that goes off at 14k feet. You can’t depend on someone free falling from, in this case, 75k or higher to open their chute. They may be out cold or injured when they hit 25k. The fact the pilot bailed indicates he was probably at a pretty low altitude when he escaped. I don’t even think it’s possible to bail out without pressurization at 100k feet. I may be wrong but it would be pretty rough. This is all quite a mystery to me.
Nobody is lasting more than 6-7 minutes without supplemental O2 at 25k feet.