He would not sell these devices. He would be someone who feeds false information into them to screw with people that are on the other end, and laugh manically while doing so.
Maybe I have an overactive conscience, but I'd feel kind of wrong about selling without disclosing that I had good reason to believe it was compromised (a serious, unfixable, almost-invisible defect), and probably nobody would buy if I told them that.
Agreed. This would be similar to knowingly selling a defective device, only much worse.
But another thought that crosses my mind is that future disclosures and research may give him new insight to inspect the equipment and try to understand the extent of potential compromise. I would replace it but then hold onto it forever. Twenty years from now, the parts could be a goldmine for documenting what will surely be a historically significant time in the world of surveillance and privacy.
If they did have that capability they might seize the equipment to maintain the illusion that they did not.
The allied forces did this during the second world war. They could not admit that German encryption had been cracked, so if their only source of knowledge about an event was through breaking of encryption, they would not act on it - even if by doing so, large numbers of civilians would die, because in the long run - far more would be saved by bringing the war to a quicker end.
That's an interesting analogy, but I think that it's not the right one here. Surely the proper analogue would be if the FBI had derived information from their remote infiltration but didn't act on it, rather than if they seized the computer to pretend that they didn't have remote access it?
If I were him I would sell them and buy new ones.