Currently a non-swap-enabled Peer can connect to other protocols like retrieval on a swap-enabled Peer. The accounting hook will cause an error when a message is sent from the swap-enabled peer blocking the send but not disconnecting the peer. This will cause most retrieve requests to always fail if there is a non-swap Peer connected on retrieval (this was encountered during devcon when nodes connected to nodes from the previous (non-swap) workshop).

Ideally a swap-enabled Peer would only connect to other swap-enabled Peers on all (or at least on all accounted) protocols.