The smart bulb doesn't have an internet connection so yes, absolutely.
Just a smart bulb itself is not really how you use that. For it to make sense you already have some kind of a gate/central device that you use to interact with the whole smart ecosystem. Such gate is often already Internet connected device (be it a Vendor specific hub, Home Assistant etc.).
An iPhone can do harm here as much as my weird Netatmo hub I have to use with my radiator valves...
Presumably the fear here is that iPhones/ipads/macs will be border routers by default and since they likely have internet access they would "force" the system to accept messages from outside the mesh.