It's a coup d'etat. If what they say is true, the only democratic recourse here is the 25th amendment, and this Op-Ed acknowledges they've considered it but won't do it. That's a hostile subversion of the Executive Office with intent to control its course - a coup.
Yeah, none of it sounds good. But one process is described in the Constitution, and the other is some anonymous, un-elected asshole making it up as they go along. I personally don't find Pence-as-author very convincing. "Lodestar" seems like a deliberate plant, especially in such a carefully written piece. The Op-Ed also uses the phrase "first principles" which is a favorite of Gen. Mattis. I think these phrases were used to throw off people trying to tell who authored the article. I don't think either of these men (Pence or Mattis) would take the first step to publish this piece, especially if they're favored to take the reins after Trump's removed. It's sets them too opposite to Trump's base too early on. I might be wrong, but if I'm playing a coup, I think it would be better to let someone more dispensable make these early forays - a senior official still, but a subordinate to the POTUS's eventual replacement.