Adding some context here.... John Oliver does get sued by some of his subjects, and it's regular enough in his show to mention that the show consulted or was advised by lawyers on what they could or couldn't say/do.
The story singles out Clarence Thomas as perhaps the worst offender, but names other Supreme Court justices with similar situations.
An important piece of this story is that there are little to no rules for Supreme Court justices, and they essentially answer to themselves- the idea that they are the highest court in the land and therefore can answer to no one else. For example, it would seem common sense to recuse themselves from cases where they're friends with people who have an interest in that case, but there's no one to make them do it.
IMO what John Oliver has done here is funny, maybe even smart. As is, people who have the money to buy the favor of a Supreme Court judge do so without repercussion. They basically pay him to sit on the court and rule in their favor. John Oliver is offering Clarence Thomas similar financial gain for the rest of his life to leave the court, and there are no current rules or laws to prevent John Oliver from doing so.
Final piece of context, the show focuses on conservative judges but realistically every judge on the Supreme Court should face the same scrutiny.