I'm going to guess that ASSCLAP, the American Society of Succubi, Corporations, Litigators, Artists, and Performers, had contacted that restaurant and reminded them that "Happy Birthday" is Under Copyright, and that every time they sang the song, they needed to pay a dime to some layabout degenerate scion who had never lifted a finger to do anything but deposit royalty checks in his whole life. And the restaurant had said, perhaps there is an alternative.
"Happy Birthday" is a horrible annoying song and if ASSCLAP kills it by the rigorous enforcement of the property fetish, it will give an opportunity for a thousand composers and mythmakers to develop successor rituals, some of which are bound to be better than Happy Birthday, which after all only dates to the 1930's and is awful.
This is a paradox of the ownership approximation to the control and distribution of goods. What does the Wutang Clan want? fame? money? for their music to be loved? If there were no piracy, I guarantee you that no person in the entire country of Mali would ever have heard of the Wutang Clan, let alone written their name on a wall. It takes a certain market momentum to persuade a starving person to part with most of a month's income (that's what a $15 CD represents when the per capita annual income is of the order of $200 per year) for some foreign griot to entertain you for 75 minutes, when your grandmother can supply hours of different songs for free.
