AFTER 21/2 years, Paul "Peewee Herman" Reubens has been exonerated of the Los Angeles D.A.'s child pornography charge against him. But Reubens - who claimed the "offensive" images were part of his art collection - pleaded guilty to a misdemeanor obscenity charge and paid a $100 fine. He must also stay away from children for three years. .... Reubens added: "I am glad the prosecutors finally dismissed the child pornography charge without me or the taxpayers having to pay for a costly, circus-like trial . . . These are certainly troubling times when our Attorney General John Ashcroft has actually ordered the semi-nude Spirit of Justice to be covered with drapes . . . [the fine and plea] seemed like the sanest way to make it end."