THE THING

...and I thought of something interesting. In both of the films about THE THING, it is made clear the "flying saucer" pilot was outside of the ship, entering the freezing cold.

Why?

Could be simple: the creature is not the species that built the saucer. The alien astronaut, realizing it was infected, opted to die in an area where the parasite could do no harm.

 Just a thought.