They're saying that there's no one to obligate in that scenario. The company made one product, then disappeared. Unless you mean their cloud providers should release their setup, but that would have bigger issues.
This could be solved with a state-mandated escrow service.
When selling anything that relies on network services, companies should be forced to provide server and client source code to an authority, which will keep it in escrow indefinitely. The company is then required to renew their "IP lock" every X weeks/months; if they fail to do so, the code is made publicly available (maybe for a small fee, to cover operational costs).
Extra red tape? Maybe. A perfect system? Probably not, as companies would likely fail to upload updates after the initial market debut; and probably someone would occasionally forget to renew locks on products they still sell. Still better than the terrible status quo? For sure.
And who is going to care to do anything with an open source smart fridge stack that maybe 10,000 or 50,000 people use? Open source only helps if someone cares..
Feels like your opening up a can of hurt if they're relying on licensed services from someone else, not like they can open source that as well.