Well the reason I brought up Sabbath in the first place is because his opinion on Rainbow reminded me of the "Ozzy era Sabbath sucks, Tony Martin was their best singer" people. When I got clarification after that, it seemed to me that his Ozzy-only loyalty towards Sabbath rubbed off onto his attitude towards Dio's other ventures.
I was using Sabbath as kind of a possible explanation of his opinion, not part of the actual opinion that baffles me. What baffles me, is liking Rainbow AT ALL, but HATING the Dio era. Regardless of his feelings on any era of Sabbath.