This seems to be a problem with all NPCs who die that use the face creation system to modify their faces - since the system employs the use of facial flexes to change facial structures, it’s on the same system as a faceposing, of course.
…This results in a very odd glitch, that, while probably minor, just seems weird.
Here’s a scientist from Anomalous Materials, probably the best example of a NPC using the face creation system in the mod, with pictures of him both alive and dead:
Notice it? All the flexes that were increased to change his facial structure have all reverted to zero.
I killed a few other scientists to check this and they all seem to suffer from the same issue.
I hope this post helps with the problem.