Merckx (doper) won the Giro and Vuelta the year after and then the triple the year after that. I'd say it didn't hamper his physiology. Are you sure you don't mean that he said he'd never better his Hour performance, not that he was never the same physically?
Nah he said it was the toughest race and he never felt the same after it. Although results prove otherwise so maybe just hyperbole to make others not try it.
Wonder if this is wise at 19 seeing as Merckx said he was never physically the same after.