It isn’t just Apple that is at risk from coronavirus. A lot of other tech companies are too, and it makes perfect sense. Apple is far from the only major US tech company that sources many of its parts from China and relies on the country for a significant portion of revenue. The other major companies which are highly exposed are Tesla (20% of its supply and demand comes from China), Dell, HP, and Corning (which looks especially vulnerable).
FINSUM: Corning has a major glass factory in Wuhan itself and relies on China for 25% of its revenue.