It's just been my experience that people talking about the "spirit of the rule" are simply trying to mask their own lack of rule knowledge with fluff and BS. Coaches use this argument to try to argue against the enforcement of a rule, and inexperienced umpires use it to try and argue a call that's not solidly founded in an actual, proper rule interpretation.
When you hear "spirit of the rule," beware. I prefer actual rule citations, which is how I've earned the nickname of "Rulebook" in my association - I wear it as a badge of honor.
...I think.
But hey, who do my fellow umpires go to for a rule interpretation/citation? Me, that's who!