I'm not exactly sure that's how it works. The constitution gives power to the FDA. This is from a statnews article involving things other than vaping but discussing the FDA.
"Others said even if he intends to overhaul the FDA, Trump may be surprised to find there are limits to what he can do.
“You can be against regulation all you want, but the Food, Drug and Cosmetic Act is not something that is malleable within executive orders,” said Dr. Sidney Wolfe, founder and senior adviser to Public Citizen’s Health Research Group, which has long battled the agency for better patient protection. “There are laws, many laws, and it took a long time to get them.”"
So I'm not really sure the government works like people think it does. Everyone just assumes POTUS can do anything and everything. Of course Trump said he was worried about the kids so it's not about questioning his stance. However even if POTUS had made a tweet saying 'dude, vaping is the kewlist shit evaahhh' he doesn't have carte blanche authority over the FDA.
Then there's this from a site called emord, "The FDA has fulfilled the founding fathers' dire prediction of what would become of an agency of the government delegated by Congress legislative power. The FDA has become tyrannical. It is a law unto itself. It is unaccountable to the Congress. It is unaccountable to the courts. It is unaccountable to the American people. It is corrupt. It is the handmaiden of the pharmaceutical industry. Its decisions have sacrificed tens of thousands of Americans lives. It has gotten away with that history of homocide. What then do we need to do to end the law violations and to return this government to its constitutional moorings?"
This is from Fordham edu at lawnet. "At a White House meeting to resolve the controversy, President Bush expressed surprise at the notion that “I’m being told that I can’t just make a decision and have it promptly executed, that the Department can’t just salute smartly and go execute whatever decision I make. Why is that?” It was in regards to a rift between the FDA and USDA.
POTUS has some power in that he can remove and replace the head of the FDA but he can't just willy nilly create or amend FDA rules and regulations. Congress gave them pretty broad scope in terms of power. Even then most things can't be achieved by executive order, even if they could because it's Trump the 9th circus gets involved and hangs it up for years even if they have no legal ground to win. POTUS also doesn't create laws, Congress does. POTUS signs off on laws but to change an existing regulation (like PMTA's) isn't just a swipe of a pen. Are we going to find a majority of Congress who thinks vaping should be simply left unregulated? Courts that would uphold an executive order if one was even attempted? This is why I say that POTUS' position on vaping has little to do with the current state of things. I'm no lawyer so there's a chance I'm wrong. It's a lot more complex though and a good amount of power struggle at the federal level than people make it out to be over who has what authority over what. Then there's other agencies like OMB who get involved, it's a real circle jerk and time suck. Think 'Vogons' from Hitchhiker's Guide to the Galaxy.