Possible spoilers all around.
From "The Things", the short story written from John Carpenter's Thing's perspective, by Peter Watts:
"...I remember Norris, betrayed by his own perfectly-copied, defective heart."
Let's remember, at this point, the appearance of the bodies' internals from two scenes. In the 1982 movie, Norris's open chest cavity revealed an entirely different composition from regular human ribs, lungs, and whatnot. Griggs' chest and abdominal section appeared to be a tangle of veins(?), instead of human internal organs (helicopter scene from the movie of 2011).
Now, does the thing leave the internal organs intact, as they are copied one to one, or is it just the appearance of human on the outside and an entirely different being inside?
If the former, wouldn't a being as advanced as to be able to build a starhip from scratch know, that an internal organ is actually misfunctioning, and proceed to correct it? Even if it had no inkling as to human anatomy, couldn't it have known the difference of a proper organ from a defective one, having copied many a human before?
If the latter, why would transformed Norris' heart condition cause him(it) to collapse and jeopardize its own existence, when in fact the heart is replaced by alien anatomy and essentially doesnt exist anymore?