I imagine there is nothing that they dislike more and wish to deny more. Think about the implications: if you can still get your nicotine hit with less risk, or even no risk, what does that imply for NRT sales?
Before we start figuring why they do anything, we have to look at the core factor - and with anything whatsoever to do with tobacco, it's to preserve NRT sales. Pharma income must be preserved above all else, and that includes disregarding the science, the resulting loss of life, the morality of their decisions, or anything else.
The starting point is always: "How can we, at the FDA, preserve and increase pharma income?"
Nothing else has the slightest relevance.