Fort Hunter is a quiet park along the Susquehanna River that many people visit to eat their lunches (usually while sitting in their cars) during the work day, or maybe take their kids to play at its playground. There is a paved walkway along the river that many use during nice weather; the mansion/park often hosts weddings, as well as annual events like Ft. Hunter Day, Garden Faire, etc. Unless it's hosting one of these big events, the park itself is very quiet & low-key, with most people keeping to themselves.

This headline is misleading - no one was preventing the guys from talking politics to anyone. Based on the lawsuit, they showed up during an event hosted at the park (an event that required admission fee/tickets), and positioned themselves near the entrance to solicit signatures for a political petition. Fort Hunter has a strict "no solicitation" policy (unless you get written permission in advance from the Dir. of Parks & Recreation). Basically, these guys didn't bother to get permission, and are now trying to spin it as a violation of free speech.

EDIT: u/CltAltAcctDel makes a fair point about not needing permission to exercise free speech, so I'll to amend my earlier statement. They probably will prevail in court.