The host SSH configuration is migrated only for upgrades from ESXi 4.1 or ESXi 5.0 x to ESXi 5.x

SSH configuration is not migrated for ESX 4.x hosts or ESXi 4.0 hosts. For these hosts, SSH access is disabled during the upgrade or migration process. You can reenable SSH access in the direct console. See the information on enabling SSH access in the vSphere Installation and Setup documentation.