The discussion had evolved into exploring the stretched option. The static route is necessary IFF (if and only if) he decides that the two nodes of the cluster need to be on separate private subnets. I've seen customers doing this because they don't want to have to stretch either the public or the private subnets between two sites.
Public subnet: 10.0.0.0/24
Private subnet: 192.168.0.0/24
Public subnet: 10.0.1.0/24
Private subnet: 192.168.1.0/24
In that case, each node will need a static route to the router that connects 192.168.0.0/24 and 192.168.1.0/24, assuming that these networks cannot be reached by the normal default gateway. The public interfaces, however, SHOULD NOT have a default gateway.