How is this a customer safety improvement? I wasn't aware that printer cartridges (even third party ones) had a tendency to spray ink in people's eyes or explode and embed shrapnel in the walls. Also, why must the printer remain on until the cartridges are replaced? What kind of harm to the printer are they concerned about should the user turn the printer off rather than leave it on for a week until they get around to ordering replacement cartridges?

It's especially sneaky to have the firmware delay its behavior until a certain date (possibly unless it is fully disclosed in the release notes, though most manufacturers don't prompt you to look at such things prior to installing the firmware). That ensures a maximum number of users will have installed the firmware prior to the enforcement date.