What is their opposition to the eruv?
If their opposition is not anti-religious and is not unevenly applied for example they want no wires in the sky becasue they cant fly kites. And there are in fact no wires including utility wires they may have a case.
However usually there is uneven enforcement of these rules its rare to find a town with no wires in the sky and nothing attached to utility poles which a NJ court in Tenafly deemed unconstitutional