I totally agree...
Since I play RPGs... 1980.. My GOD I feel OLD
I apply the following rules...
The Books are references and guidances not the Rules
I work my A... to provide a good & enjoyable gaming session therefore I AM THE RULES.* without being a dictator.
1) I generally allow any questions or shorts validations of a rule then we may have a few exchanges but after I made my ruling it is final. THE DM IS ALWAYS RIGHT. All of my players will quickly prompt this fact to any arguing element. You can point out this fact to your player and soon they will be supporting you when a problem occurs. It is best for the game!
2) If a player want to raise a technical issue, he must be prepared. He has to research his case before I pause the game. He can't say this spell works that way without any support or being ready with the spell description in hand. For anything else my judgement & experience will do as well.
3) If the matter requires a long and complex evaluation, I quickly rule what makes sense. And I may correct it in a future gaming session or reverse time (Standard DM abilities) and correct the point if it doesn't affect too much the gaming.
4) My Games/My rules, as long as they are applied fairly to all. The quality, the roleplaying and the pure fun of the game should have priority. Your judgement will guide you.
5) I don't have to justify any of my callings. Why.. the plot or action is planned that way... a factor or elements are unknown or nor considered by the players...that FACT must happen it is in the story line...etc. The DM again is ALWAYS RIGHT...
Hope it will be of some help...
Voronaxe