Here's an update on the previous post on this subject, which I've been looking into at CampusReform.org:
To further research this story, I called the town of Campbell, which is the intended site of the rally. I reached Denise Sarigianopoulos, who very kindly agreed to speak with me on the subject.
She spoke well of Freeborn and the YAL group, but explained that the gathering was originally falsely represented to the town as a "support the troops" event -- and that this would have been something the town would have supported and allowed to continue without a police presence for security.
"If it were for the troops, we wouldn't need police protection. We would probably have marched with them," Sarigianopoulos said. She explained that Campbell is, like many local and regional governments, in "fiscal emergency" and unable to pay for the extra police presence town officials decided was necessary at the pro-Second Amendment rally.
Sarigianopoulos' point is understandable (and the town's concern for careful fiscal policy admirable)...but it's also unconstitutional.