I half agree with him. I agree that Muzak is crap and should be banned from all public places for the rest of time, and that those who inflict it on us should be tarred and feathered and locked in a room with a Muzak CD playing on a loop for a minimum of five years, but I don't necessarily agree that passive listening is always a bad thing. If you're concentrating on something else I don't think there's anything harmful in it.
A late 19th/early 20th century musician/sociologist Adorno believed that passive listening was a way for the "culture industry" to control us by making us think we're getting escapism from the mundanity of everyday life, when in actual fact it's things like mass-produced, consumerist music that are making us feel bored and depressed in the first place, but then we listen to it for escapism, etc., and so it goes round in a circle. He also mentions "pseudo-individualism" - where the industry try to make us think we have our own musical tastes and personalities by dressing bands up differently, giving them different images etc., when in actual fact their differences are so superficial we might as well all be listening to the same one.
However, I think that Muzak's enormous lack of value lies in its vapid, unappealing, boringness rather than its harmfulness. It is quite simply the most worthless rubbish out there, and yet they pump it out into supermarkets and other busy places under the misguided idea that it's inoffensive. They don't have a clue. It's the lowest of the low. Rant, rant ...
Jas