It's annoying, but we've always accepted new oil standards and new minimum requirements. My 1980 Buick's manual specifies a minimum standard of API SE-rated oil and recommends SF which did not even exist when the manual was printed (it says SF will be introduced soon).
VW has required the use of VW-approved oils for years.
We also accept coolant, transmission fluid, and differential fluid requirements too.
the article mentioned possible warranty issues by NOT using their oil. as of now, this is simply not true, but GM(government motors) could have future legislation on their side i suppose.
edit: one BITOG guy had it right when he claimed that manufacturers are making it more difficult for independent shops and do-it-yourself owners to maintain vehicles. i'm a former GM guy(my wife still is) who will likely never own anything but a 4 cyl car for the rest of my life(due to easier/cheaper maintenance). if GM wants to pull these types of things, well they will continue to lose my business.