Why drag Shane and Rick all the way out to the school, have Shane punk Rick in the face, the knuckle-grinder of a battle fit for the Disney stunt show, and even put Rick in the perfect, justified position to pull a Shane-to-Otis on Shane? I know, I know, Rick represents 'humanity' and 'rule of law' and all that, but come on. What a fish story of a conflict. All we got out of it is Rick is still in charge, "for now", and we wait another episode or two before they dispatch Shane. Do it, man, just do it.
Not to mention the smooth move of opening up what had been a sealed-in fence, unleashing more walkers on wherever they are. Least they could have done is tidied up after them.