Why would they bother? They make all their money on the ink cartridges. If this drives more cartridge sales it’s a win/win for them. They generally don’t make much, if anything, on consumer ink jet printers themselves
Many corporate and government types, especially lawyers, want control. They will go broke trying to control everyone and everything.
Heck, it may actually save them money. At one point they were losing money on every printer sale and making it back in ink No idea if that’s still the case.
It just seems easier to fire off a cease and desist than to take a risk of other people messing around with your ecosystem.
This already happens for basically every commercially-available ink cartridge.