The question at hand - is it right to withhold evidence that could change the outcome of a case, even if it doesn't speak directly to the guilt or innocence of the defendant in the charges brought? (In this case, an unjustified traffic stop for a bad tail light led to an allegedly justified DWI arrest.)
IMO the prosecutor made the right decision to dismiss in this case, but it's still an interesting glimpse at the thought processes behind decisions whether to release exculpatory information - essentially haggling over the definition of what is "exculpatory" - especially in departments that don't have an openness policy.
An assistant county prosecutor from Richmond, TX offered this light-hearted definition of what is "exculpatory":
exculpatory - adj. 1) something courts determine you should have disclosed after you've already withheld it. 2) to be considering the possibilities of living life as the former wife of actor Robert Culp.