The thing is, Fox is all about ratings... News, Fiction... whatever... the three most important things are Ratings, Ratings, Ratings.
If they (as an organization) are convinced that Trump will move to obscurity in 2 years, that they will lose their protection from FCC violations of equal time, libel suits, and loss of contestants (err.. I mean guests)... It's prolly time for them to start establishing the "we don't work for him (anymore)" theory.
Fox is not
all about ratings. Fox News is crafted to advance the self interests of those who control it's content. As THE #1 source of right-wing propaganda in the world, they have massive influence over politics and economics. Murdoch, the rest of their board (which includes Paul Ryan), CEO, and their major show hosts like Tucker Carlson all have many financial interests that extend beyond the profits of the Fox News channel.
Economic interest means interest in particular political outcomes, particularly ensuring that the 1% pay as little taxes as possible, that corporations can get away with anything they want, that the rich have total control over government policy, and that none of the unearned privilege that their race has enjoyed are threatened. By extension, fueling xenophobia and white nationalism is also in their interests, which is why they constantly do it. Granted, the many millions of white nationalists, homophobes, and misogynists in the US are the primary source of ratings and thus direct profits to FOX News. However, Fox New's controllers also indirectly profit politically and financially from stoking this bigotries because it distracts the majority of their economic victims (the poor and "working class") from these viewers real political and economic enemies, the 1% and most multinational corporations. Also, by stoking the fears of bigots they drive them to support the party of bigotry, the GOP, which just so happens (by design) to also be the party of extreme right wing economic ideology.
Note that while dishonest rightists will use the strawman of "nice conspiracy theory", these empirically supported realities require nothing other than that those who run Fox Corporation are acting out of greedy self interest.