Actually it was a couple of big ABC affiliate owners that started the avalanche, and ABC followed…not any government pressure.
You can certainly speculate that the these affiliates had an ulterior motive in their actions to curry favor with the Trump administration, but it’s not unreasonable nor unheard of for station affiliates to make decisions about content and programming to avoid alienating or offending a large portion of the markets they serve or the advertisers that pay their bills.
In the end this is about eyeballs and advertising dollars and it’s no more nefarious than that.