I'm sorry, but in this case I disagree. Whether the device was smart or not is irrelevant.
If there is a connected device in a supposedly otherwise secure network that allows traffic in or calls home, that device is an attack vector. Pure and simple. The only safe assumption is that such a thing is an insecure, unmaintainable black box that was put together by the cheapest fly-by-night contractor.
A "smart" device is worse, and guaranteed to be a dumpster fire. One should not be allowed anywhere near a secure network, regardless of its function. Printers, VoIP phones, climate control systems, ... they're all the same.