Billionaire grocer and onetime NYC mayoral candidate John Catsimatidis has the food industry scratching its head. The owner of the Gristedes supermarket chain just pumped substantial dough into money-losing rival D’Agostino, which was struggling to pay its bills and keep merchandise on its shelves this summer. Catsimatidis is propping up family-owned D’Agostino’s because “we wanted...