The GlenKaren water resistant polish includes sodium bentonite, which is a clay. This clay makes the polish in the jar feel a little gritty, and although the polish becomes smooth as it is rubbed into the shoe, some people don’t like the feel of the clay and are concerned about its effect on the leather.
It should also be noted that the water resistant polish will not water proof the shoe, but simply slow down the absorption of water into the protein fibers. You could get better water proofing by using Sno-Seal, but I probably wouldn’t use it on a dress/business shoe.
Most water proofing products don’t hermetically seal the leather but do put a degree of water barrier on (or slightly into) the surface side of the leather. There is an actual difference between the moisture content in the leather produced by sweat and exposed to the looser corium side of the leather, versus the grain side coated in a water barrier. The moisture content in the leather (as water vapor) takes less vapor pressure to evaporate at the surface than a raindrop or puddle of water does to pass the water barrier. This is an aspect of Water Activity which is the science of how these things work.
Other factors to consider when thinking about moisture from the inside versus moisture from the outside. Most dress/business shoes are lined and the liner also absorbs and retains moisture. One of the reasons to use wooden shoe trees is to allow the wood to absorb the moisture from the liner (unless you have lacquered shoe trees).
Most dress/business shoes have a toe puff (that makes the toe of the shoe stiff) and an internal heel counter which will impede (or completely stop) moisture from traveling from the inside of the shoe to the outside (and visa versa) in those areas.
A foot has approximately 125,000 sweat glands, most of them are in the sole of the foot, not the instep, so most of the moisture that evaporates through the shoe upper will go through the quarters.
All that being said, a thick wax, oil or silicone barrier on (or in) the leather can impede the moisture (and/or air) enough as to not allow evaporation and the trapped moisture (which is different than Bound Water) can cause dry rot over time.