I know the real reason that the kids were arrested...
They were erecting a structure without the proper city and county permits, and without the proper inspections by city, county, state, and federal inspectors, like OSHA. They didn't have an environmental impact study done either.
Governments can't allow this sort of action to take place. The kids are obviously anarchists, who refused to wait for the process to complete (and never paid any of the fees, taxes, and bribes that are normally paid).
Of course, had they gone through all the paperwork, had the study done, and paid all the money, it would have been half past summer before they could have gotten started on their "snow fort!"
Mark
I don't think building a snow fort was the only erection thay had in mind.