Pilots would have to blow 0.0 but that doesn't mean zero evidence of alcohol. In 4 hours you can metabolise around 4 standard drinks out of your bloodstream. It's not like drugs where any trace is bad because it's illegal.
That said, I'm not sure I am on board with the explanation. It could just be that with everything going on in a cockpit it wasn't noticed.
A fever is, at it’s core, an increase in metabolic rate. Your hypothalamus is telling your body that it’s temperature set point is higher than usual, and it takes energy to raise your temperature. I don’t see how a difference in air pressure would have a similar effect.
other way around - reduced air pressure is reduced oxygen, which is lower metabolism. Higher metabolism causes EtOH degradation to go more quickly. Fever is higher metabolism.
Your blood oxygenation will stay at 95-99% even while in a cabin.
Metabolism in aircraft is pretty low: you’re generally sitting idle, but I think the alcohol metabolism is still constant except the terminal metabolism.
Fever is partly metabolism, but largely reduced cooling.
