Not going to get into another circular argument that the solution to not being able to vape were "they" want is to vape nowhere at all. The only people who win that one are the people opposed to any vaping, any place, any time.
Not seeing OK as the culprit. Isn't that a private service? Also it says Please Refrain - Sounds like a Request from an Administrator, Not a Policy enactment.
Likely another - We don't know, so must be Bad - train of thought.
More likely "someone complained, they don't know, but we don't have to balls to stand up to illogical complaints, so rather than do any real thinking about matters we just caved in."
I'm gonna start a campaign against the color pink and see if I can get wearing anything pink banned in public buildings. I don't need a logical reason, apparently I just have to complain.