WIll has also his share of right, as no comparison could be made with a unexisting OTU underlying reality, at least until OTU was described.
Obviously a game universe has to be described before it can apply. Once it has been described, though, it generally trumphs any rules, as long as the description is reasonable.
For example, as I mentioned above, according to the CT combat rules, it's impossible to kill an average human with one shot from a handgun. Nevertheless, if I run an adventure that featured a strong, agile, healthy NPC being hit in the heart by a single shot and killed outright (just before he can tell the PCs the crucial plot details

On the other hand, if I told my players that the NPC had been hit by a handgun and disintegrated with all his clothes and possessions so there's no body to search for clues, I think my players would be fully entitled to give me the raspberry. And not just because the rules says a handgun doesn't disintegrate what it hits, but also because the players' knowledge of the underlying reality makes it perfectly possible that someone could be killed outright by a single shot but utterly impossible that he could be disintegrated.
Hans