I've done similar experiments in the past a couple of times during periods where I found myself conscious while still in light NREM. I was curious if I could make gentle shifts in body position or even briefly crack my eyes open and look into my room without disturbing my state of sleep, and tried it. As far as I could tell, I was easily able to do so without pulling myself (too much) back toward wakefulness. I even tried talking once, though it seemed difficult for some reason (I was unable to conclude with certainty whether it was in fact physically difficult or if I was just afraid to push my luck and wake myself up).
This supports the idea that people really shouldn't worry about small things like swallowing or minor adjustment in position during a WILD dive; as long as one doesn't put much thought or attach any concern or significance to them, it should be fine. Just let them be as natural as those same actions that you do nearly unconsciously while falling asleep normally without trying to WILD.