For Roberts to have said that he was not going to follow Roe as an appellate judge would have been wrong. I blasted Farah because he let his views on how Roberts should address a particular issue -- abortion -- override generally accepted judicial principles that are accepted by almost everyone.
His editorial is also symptomatic of the problems you get when lay persons unfamiliar with legal phrasing start parsing words. "Settled law" simply means that the existing case law on a certain issue is clear. It doesn't mean that its correct, and I've seen lots of lower judges observe that they might not agree with something, but it was settled law so they were stuck with it. Overturning "settled law" requires action by a higher court, often the court of last resort.
"Unsettled law" means that there are some gaps in the law, or disagreements among courts of equal stature, so other courts have the freedom to make their own judgments. Roberts was simply using those phrases in that sense, and for Farah to jump on him for that just shows that Farah doesn't know what he's talking about.