I think you are misreading him on this, and the rest of the court too.
Entirely possible that I am. His previous opinion makes him unpredictable. He seemed to go to great lengths to find Obamacare constitutional, quite possibly changing his mind late in the game. I base my read on him wanting to salvage some credibility, while still wanting to keep Obamacare intact. He could do that by signing on to a minority opinion.
It’s also possible that he could find this particular part of Obamacare offensive to the Constitution, and perhaps even take the lead in requiring that it be altered. That’s a far different thing from killing the law altogether. This route could allow him to remain consistent with his original opinion, while attempting to help his reputation.
I’m glad I don’t have to put money on what John Roberts will do.