"The vendor won't let me build my own firmware updates for this device, therefore I will cut the write-enable pin, so that their official updates won't work either."
Is a dog in a manger type of tactic
It might make sense in the short term, in some very specific situation, where your own inability to yield to the enemy's demand is an advantege (you could argue Firefox shouldn't support EME for that reason).
But the long-term goal should be for you to be able to flash your own firmware.