"The anti [Obergefell] forces will get Thomas and probably Alito. Roberts was strongly against at the time but..."

"...has been careful to treat it as legitimate precedent since. Gorsuch usually sides with religious litigants but also wrote Bostock, the most important gay rights decision in years, and Roberts raised eyebrows by joining him. Most people who know Barrett and Kavanaugh believe them to have zero appetite for reopening this issue. Trump isn't pushing for it. Granting cert takes four votes, overturning a case five. I don't see [Kim] Davis getting up even to three on the question of whether to overturn Obergefell. Each time I write a version of this prediction I get called rude names, as if I were consciously misleading people for some fell purpose. But as someone with real rights of my own at stake, I'm just trying to give you my honest reading. We'll probably know within three months whether the Court will hear Davis's case and if so on what question presented. Save your anger till then."

Walter Olson, quoted by Ilya Somin, in "Why the Supreme Court is Highly Unlikely to Overturn Obergefell in the Kim Davis Case/My Cato Institute colleague Walter Olson explains" (Reason).

Should we "save [our] anger" if we don't want Obergefell overruled? Even if that's unlikely, now might be a good time to demonstrate how much it would hurt, before things escalate.

Meanwhile, I'm interested in Olson's dipping into the archaic to write "I get called rude names, as if I were consciously misleading people for some fell purpose." Fell! Why not "evil" or "nefarious"?

One answer is that he was influenced by the last syllable of "Obergefell." I don't think one would do that consciously. 

I'd guess Olson felt motivated to sound deeply literary. Some historical examples of the adjectival "fell" from the OED):

1747 I will risque all consequences, said the fell wretch. S. Richardson, Clarissa

1812 And earth from fellest foemen purge. Lord Byron, Childe Harold

1813 His fell design. W. Scott, Rokeby

1847 Even the fell Furies are appeased. R. W. Emerson, Poems