Without Find my iPhone the device can't be remotely wiped but note that the iPod touch requires a Wi-Fi connection to be able to be erased remotely. Without that the device can't recieve the order to wipe itself until there is a connection to Wi-Fi.
Also there is the option that the device is erasing all data after 10 wrong passcode entries. This has to be enabled in Settings --> Passcode and requires a Passcode. Was the device locked with a passcode? With that the thief can't access your data atleast.
And if the thief wipes the device by restoring using iTunes for example, all data is lost and Activation Lock should be enabled if the iPod is bound to an iCloud account.