Hitchens didn’t really address Buddhism in any meaningful way. He made a quip once about the Buddhist saying this glass of scotch isn’t really there and Hitchens’ response was something about how he rejected that take because he enjoyed the scotch.
He seemed to dismiss it because it was a religion rather than address any of its positions in a substantial way. Probably because he couldn’t give as forceful or witty a counter argument to it as he could Christianity.