Well if the court didn't engage in clearly partisan politics, maybe the liberal justices wouldn't have anything to criticize.
Does he realize how bad it looks when he voices that his problem is criticism and not like, I don't know, taking money from political interests? Or refusing to recuse in cases where there's a relative directly involved?
John Roberts Begs the Liberal Justices to Stop Criticizing the Court (newrepublic.com)
The chief justice doesn’t like his conservative Supreme Court colleagues getting called out for judicial overreach.