I generally agree with this advice, but I think it's poor form to give it to someone in the middle of growing a good starter. There are risks with a more open fermentation. Some people have a really bad time with just using foil (although the majority, myself included, has it work perfectly fine). If the guy has a beer in mind, I'd be inclined to leave it be and just gently point him in an alternative/better direction, rather than do something that can jeopardize a good sanitary starter for a beer he's already got in the works....