Harford County school officials insist that their decision Monday to rescind a ban on field trips to Baltimore's cultural institutions had nothing to do with the public attention to the issue since the prohibition was first reported in the Aegis last week, nor with the outcry from public officials, including County Executive Barry Glassman's voiced hope that the system would revisit the issue. Instead, they say, it was the result of routine re-evaluation of the likelihood of riots in the city. Yeah, right. Just like the decision a week before to allow Harford students to participate in sports games and tournaments in the city had everything to do with a well-grounded determination that such events have better security than, say, the Baltimore Museum of Art and not the fact that parents went nuts when they found out the previously unpublicized policy might keep their kids from qualifying for the playoffs.