Harley doesn't just "have access to the 500cc single." Harley created that horrible engine by lopping off one cylinder of a Sportster engine and then forced Buell to create a bike around it and to sell the resultant product under their name. Because Harley didn't want a beginner bike with normal (non-cruiser) ergonomics to sport the Harley Davidson name.
So f*** Harley Davidson. They shut down Buell, turning down handsome offers from Bombardier to buy Buell and keep the plant open. Harley Davidson laid off 180-200 workers at Buell out just before Christmas in the worst recession we've seen in decades, all out of spite, political in-fighting, and personal vendettas against Erik Buell.