If she ran in a primary, she’d be firmly in the Larry Hogan lane, which might constitute about 5 percent of the Republican electorate total. It’s quite possible that those voters are themselves so disaffected from the GOP that Cheney wouldn’t be denying them to any other non-Republican candidate. But if that’s wrong, or if she got some traction, she’d only be taking voters from some other, more viable, alternative to Trump. She might not even make it on the debate stage with Trump, if the party writes rules to exclude her.

What possibly would make such a run worth the risk of, at least at the margins, making it more likely that Trump wins the nomination again?

An independent run wouldn’t make any more sense. Again, her share of the vote would likely be tiny. In 2020, Libertarian candidate Jo Jorgenson got 1.18 percent of the vote. Even if Cheney could get more, the chances are that she’d be a place for Republicans repulsed by Trump to park their votes rather than go all the way to Biden. This means, just as with a prospective primary run, she’d be helping Trump at the margins.

Captain Ahab may have made a few mistakes in judgment in his stewardship of the Pequod, but at least he never allowed himself to affirmatively assist his great adversary, the White Whale.