Killswitch -- I'm not questioning the NASA report dude, but a leak in a space suit is hardly full-blown contact to a vacuum.
The suit lasted for a long time because, depending on where the leak was, it must not have grown any larger. The suits are designed with, among other things, that sort of failsafe.
Also, while the individual was losing oxygen to the suit, he was also giving off body heat as well as additional oxygen from the suit's own supplies.
Because a vacuum has no air, it doesn't displace temperature with the transferral of gases. Once the oxygen runs out, the individual's blood boils but not before freezing solid.
I've seen what they've done with Hollywood -- people don't actually explode in the vacuum of space. Instead, their bodies swell slightly as their blood comes to a boil, then they freeze solid. They never actually explode.
The NASA report was correct, but a vacuum can easily be simulated in a classroom -- we did it several times in Physics and Astronomy. Liquids come to a boil, and the temperature of the vacuum of space is undeniable.
The NASA report is accurate for those who are in a protective suit or are not in full exposure. But for a naked human, the effects are very different.
Though the facehuggers do give life-support to their victims, it may not be concentrated oxygen which they use. They could simply be circulating the surrounding atmosphere (if any) through their bodies and into their hosts. Either way, I highly doubt they breathe due to their existence in the xenomorph eggs all that time in the first film.
Also, let's not forget the molten lead scene in Alien 3. With the gaps in their face that metal surely entered its body, and it was obviously extremely hot during that entire time. If the xenomorph had lungs or needed to breathe, its lungs would have collapsed due to the hot air. The same thing happens when breathing over a fire.