The article gave me the opposite impression. Basically their database contains lawn signs and bumper stickers on accident - they save all images where text is found but they keep it just in case it had a license plate (because they aren’t sure what is or isn’t a license plate). These kinds of databases are so massive there’s little to no human eyes on images. Anyway I don’t think it would be very hard to send garbage into their database.
Assuming the desktop takes the same power saving techniques from their laptops, there is no real reason to turn it off.