GP was referencing oxygen in regards to combustion, not the cockpit. The space suits weren't because of the cockpit altitude (when the cockpit was pressurized)

GP was referencing oxygen in regards to combustion, not the cockpit. The space suits weren't because of the cockpit altitude (when the cockpit was pressurized), they were because the crew were operating well above the Armstrong Limit and no amount of oxygen could keep them awake in the event of depressurization without the suit.