Guidance isn't enforceable, so people are at (legal) liberty to disregard it. The question is whether it counts as a meeting of 2 or more people indoors, which as the definition of "indoors" being used is "subject to the smoking ban" I would argue that since the last rule change it is (but probably wasn't before).
Though for at least the instructor, it's in the course of their work which was a fairly wide get-out clause for many situations.