Well that guy is one of the most experienced technical experts on ecigs around, so we could at least give him the benefit of the doubt. I agree with him because I've analysed about three dozen
ecig vapour tests in detail, and a common feature of the more accurate vapour [1] analyses (not the liquid of course - as you say, there isn't much water in it) is that they all give a water content in the vapour as over 50%, and there is plenty of evidence that the vapour (again, not the liquid) is mostly water vapour.
ecig vapour is a water-based mist, containing mostly water (over 50%), and with the next largest components typically PG at 6%, VG at 5%, nicotine at 1%, and flavourings the remainder.
The reason for the high water content compared to the liquid is (a) the two things are not directly comparable (see below); (b) the purpose of the PG and VG content of any stage fogger or
ecig is to bind to and make visible the atmospheric water; and (c) inhaled and exhaled vapour will contain very large quantities of water vapour indeed, because there's lots of water vapour present in the respiratory tract - the purpose and the function of PG (and even glycerine) is to bind to water vapour and create larger aerosolised droplets so that they can be felt in the throat and seen in the air (to make water vapour act like smoke). You have probably seen the mist that people exhale made visible on a cold morning; that mist of water vapour is always there of course, and the purpose of the PG etc (among other things) is to do the same as a cold morning does: agglomerate the mist droplets.
No doubt you are aware that the proportions of ingredients in the vapour are different from the liquid?
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