I assume that the variability of stomach contents is accounted for in the creation of the mechanism, at least to some degree. (This may be part of why some meds come with instructions to eat or not eat before or after taking them - such instructions are relatively common, though I don't remember if they correlate with sustained release mechanisms, and I know there can be other reasons for those directions.) Dampening the pills and then drying them out seems like it could have a different effect than drinking water when taking them, and exposing them to other chemicals could also have unexpected effects, and it's better to be safe than sorry.