An observation I've made in my last viewing is that the "survivors" by the end are all not formally educated, or basic practical trends would assess that as likely.
Nauls - Cook
Childs - Mechanic
Garry - Previous outpost leader/manager
MacReady - pilot
Did "The Thing" want to assimilate scientists first so that the remaining human survivors would have less knowledge to work with to better defend themselves? Also would "assimilation" include taking some of the knowledge/learning/memory of the infected? Did "The Thing" get all those decades of training, experience and education from Blair when he was absorbed/infected? That would be a powerful way to learn how to adapt, survive and hunt down your enemies.
To be fair, a research outpost will have the majority of personnel be science/STEM/technicals, etc. Also Palmer was a mechanic and he was infected too. Then Bennings might have just been a target of opportunity.
Also wouldn't you want to infect Nauls first and foremost? If he can infect the food, then he can naturally and seamlessly infect everyone quickly.
The film forces you to ask a lot of questions. You have to give Carpenter credit. He mixed in enough within the film to leave doubt around every corner. Not so much that it all becomes impossible, but just enough to hook the viewer.