No they don't think it has to do with nicotine (not the discrepancy at least) for this study they more or less focused on cinnamaldehyde which is the compound that gives cinnamon it's flavor (it's also a known irritant and is used to kill mold, fungus and some other things).
I would assume that they've focused on cinnamaldehyde because it's most likely a common ingredient in e-liquid not only for the flavor but as it's an irritant (watch the fools doing the "cinnamon challenge" on YouTube for a good example of just how bad it can get) it's quite possibly been added to allot of liquids to increase their throat hit especially for those liquids that are aimed at recent former smokers that really look for that feeling to more closely imitate cigarettes.
I would assume that they've focused on cinnamaldehyde because it's most likely a common ingredient in e-liquid not only for the flavor but as it's an irritant (watch the fools doing the "cinnamon challenge" on YouTube for a good example of just how bad it can get) it's quite possibly been added to allot of liquids to increase their throat hit especially for those liquids that are aimed at recent former smokers that really look for that feeling to more closely imitate cigarettes.