Ultimately I can't make a conclusion, although I thought about casing some Virginia with Himalayan pink sea salt just so that I could put it in a jar and then switch it back and forth between my fridge until it grows pink "bloom".
If it's science, we should be able to replicate the effect.
Replication might be difficult, since we don't know what exactly has been added to the tobacco over time (harvest to tin). Best bet, I would think, is to have the crystals analyzed. Who volunteers to pay for it? ;-)
I think that there are probably several distinct phenomena going on here that collectively pass as "plume". Some is biological, no doubt. But these are crystals. What we need is a pipe smoker that works in university science research who would be willing to slip in some extracurricular experimentation....
Confusing that, is that some molds will be reflective in small amounts, like a sealed container where there isn't much air to let them grow. And they can even sparkle. So a white powder could just be mold that started to grow and ran out of fuel.
Mold inspectors have the same issues diagnosing "is it mold or efflorescence?" when examining buildings.
Looking at the microscope photo in the OP's brown sugar post, it appears to not be a mold. In the ref: link above, you can see what they would look for under a high powered microscope.