You don't have to guess that the DA will drop the charges, the article literally explained that Novak was arrested, tried, and acquitted. No charges were dropped, a jury found him not guilty.

Though (and this is speculative) it may be because the state could not prove that Novak's conduct was intentional/"knowing" . Novak may have thought that his content was obviously satirical and would not disrupt anything, which moves it out of "it's a crime" space and into the "stupid mistake" type space when people actually mistook his satire for reality.