A Restrictive Peering Policy is a reflection of a Restrictive Peering Inclination - a general willingness NOT to peer.
There may be a written Peering Policy but most likely it is covered under a non-disclosure agreement.
There is a general anonymosity against those with Restrictive Peering Policies. They are viewed as operating in an anti-social fashion, not seeing the value of the other parties, seeking to extract incremental revenue from a party providing value to their customers.
Peering Policies can be described in these these rough categories:
Definition: An Open Peering Policy is an articulation of an inclination to peer with anyone.
Definition: A Selective Peering Policy is an articulation of an inclination to peer, but with some conditions.
Definition: A Restrictive Peering Policy is an articulation of an inclination not to peer with any more entities.
Definition: A No-Peering Policy is an articulation of an inclination not to peer at all.