That McCain is opposing an extreme right-wing approach of "repeal" only should not be surprising to ANY GOP member.

McCain was reportedly troubled by the right-wing-nut approach to politics that was emerging back when he was running for President.  It was, reportedly, so troubling that it probably undermined his own vigor as a candidate.

There's a difference between conservatism (McCain) and right-wing-nut (e.g. Tea Party, etc.) power obsession (e.g. McConnell), racism (e.g. Trump) that fuels the current GOP repeal proposal.

McCain's conservatism requires a consideration of the impact of Federal policies on the WHOLE of Federal budget and operations.  The current GOP power cabal is obsessed with a single action that would make the tribe members (many, if not most either enormously stupid or enormously greedy) cheer wildly, damn the consequences.

McCain is acting like a great American politician.  McConnell, Graham, Cassidy et al. are acting like  leaders of a tribe destined to die