IMO, no it can't.We installed a service rated double throw manual transfer switch ahead of our original 400 amp service. Can the bonding stay in the original MDP? The MDP is located adjacent to the new MTS.
I am going with no.
230.82 prohibits transfer switches on the supply side of the service disconnecting means so that means the transfer switch has become the service disconnecting means (or you install a new service disconnect on the supply side of the transfer) and the original panel is now a 'sub panel'.