Yes, that is likely. Although Danfoss seems to have their own controllers, I think that you are right, that the attack was not an 'Internet connected fridge', but an HVAC or FMS (Facilities Management System) that was connected to the fridges.

My mistake. It is stupider than that. Facepalm.

https://www.claroty.com/team82/research/freeze-the-controlle...