The article is about motor oil for diesel engines, NOT diesel fuel.
I hadn't realized that now there are different recommendations for motor oil specifications (based on the additives) used in gasoline or diesel engines. Back when I was on the family farm (1970's - 1980's) and changed motor oil, the only difference we paid attention to was that generally diesel engines needed a heavier viscosity in the summer and a lighter viscosity in the winter, so 10W30 for the cars and pickups, 5W40 for the diesel tractors. "Old timers" didn't trust the "new and modern" multi viscosity oils and would always change oil weight according to the season.
I checked the American Petroleum Institute web site. They are the ones who set the standards for different petroleum products and one will find an API classification on every container of motor oil. They don't speak of any shortages.
I checked the NAPA (National Auto Parts Association, a franchise auto parts supplier in the northwest, I don't know how widespread they are) web site. They don't speak of any shortages and even have some of their diesel engine oil on sale, which they wouldn't do if there was a shortage.