I think this is a fairly strained interpretation to try to defend the idea that the court is iron-locked into the "liberal 4" + "conservative 4" + Kennedy divide (casting a different divide as Roberts trying to create an illusion about the court), and it falls down when you have high profile cases like the today's Hollingsworth v. Perry [1] where the majority is made up of Roberts, Scalia, Ginsberg, Breyer, and Kagan.
[1] http://www.supremecourt.gov/opinions/12pdf/12-144_8ok0.pdf
Why? So he doesn't have a problem getting "re-elected?" I'm not sure why you think he is worried about the appearance of the court in that way.
Remember, the Court gave itself the powers it has in Marbury vs. Madison, and has at times had folks like Jackson go "let them enforce it". If public opinion turns against the Court, politicians can as well.