The appropriate way to create policies for multiple tenants is to create multiple policies.
neutron rbac-create admin-ext --action access_as_external --target-tenant a654338c862f401a8665c3fbed289a75 --type network
neutron rbac-create admin-ext --action access_as_external --target-tenant b0dc258dd3204bf99750589d1ed23996 --type network
The appropriate way to create policies for multiple tenants is to create multiple policies.
neutron rbac-create admin-ext --action access_as_external --target-tenant a654338c862f401 a8665c3fbed289a 75 --type network
neutron rbac-create admin-ext --action access_as_external --target-tenant b0dc258dd3204bf 99750589d1ed239 96 --type network