They could follow their oath of office if possible (for example, if assisting the president when requested and defending the constitution were not in opposition.)
That's the only third option.
As I read the op-ed, there is no admission than any oaths of office have been violated.
Meanwhile, the White House in January simply blew off a congressional deadline to impose new Russia sanctions as required in a July 2017 bill that passed 98-2 in the Senate and 419-3 in the House.
Of course there's the argument that "2 wrongs don't make a right," but sometimes actually it does work out that one wrong mitigates the impact of the other wrong.
I'm not knowledgeable enough about how sanctions work to understand exactly why the WH had the discretion to ignore Congress on this issue, but it's possible Trump just worked out, correctly, that Congress wasn't going to do jack**** if he ignored the legislation because they were a bunch of wimps.
Jim Mattis (ETA: reportedly) decided not to launch an offensive to kill Assad even though that's what Trump wanted. Did he betray his oath of office? I imagine he just said "Yes Sir" to Trump, then gave the president 3 scenarios, none of which involved assassinating Assad. This is how power works in actuality, not how it works in the idealized civics lessons we got in grade school or whenever.
The op-ed's main function, IMO, was to signal that Woodward's book essentially got things right. Otherwise it was virtually content-free. Vowing to slow down hasty and ill-considered decisions doesn't in itself automatically mean that anyone is betraying an oath. It could mean just double- and triple-teaming the president, buying time, finding a plausible excuse to delay a memo's progress through the pipeline, keeping an email exchange going in a way that obscures who exactly is supposed to make the next move. IOW passing the buck.
I think it's quite possible that the op-ed was at least loosely coordinated with the release of Bob Woodward's book. I had also sensed for some time that McCain's death was going to promote at least the appearance of soul-searching and bipartisanship. On his end McCain milked his passing for all it was worth. He knew he was going to have an impressive funeral along with all that lying in state and flag-draped coffins and widow weeping on his casket. I imagine he got a kick out of imagining the results.
IMO he knew at the end that he too was complicit in enabling Trump. He doesn't get off scot-free either.