If the only usecase is monitoring, then why make the fridges anything else but report-only?

No firmware updates. no admin configuration. no ssh backdoors. just a transmit-only system

because the report code might have bugs

	▲	AlotOfReading 7 hours ago \| parent [-]
		If it were transmit only, you could put it behind a data diode and buggy report code wouldn't matter. Even better, validating the code is a lot easier if it doesn't accept attacker input.