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Who knows what backdoors and security vulnerabilities every motherboard in every computer might have?
So you shouldn't use any computer?
Printers are connected to the Internet these days, and they are much less commonly audited than motherboards or CPUs.
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So are computers connected to the Internet these days ... that was the point of not connecting it to any network, as I stated.
Connecting the printer to any network of course violates that idea also.