A recent decision in Kentucky:

https://www.washingtonpost.com/news/volokh-conspiracy/wp/2017/05/14/kentucky-court-rejects-government-attempt-to-punish-printer-for-refusing-to-print-lexington-gay-pride-festival-t-shirt/?utm_term=.7b9a055be0de

An important quote from the decision:

“…the right of free speech does not guarantee to any person the right to use someone else’s property, even property owned by the government and dedicated to other purposes, as a stage to express ideas. …”

Not that this will carry much weight in progressive Trenton (or progressive Ridgewood), but this is a valid opinion