That's a good way of putting it, even though I disagree with your implication that implementing public health guidance was the political "line" was crossed.

My take is that in the (maybe distant) past, facts and observable events were beyond the line that politics should cross. If anyone could observe something was happening, then politics had no business stepping in and distorting that reality. We could all see that people were dying of COVID. It was indeed real, and an observable crisis. But politics stepped in and crossed the "reality distortion line" and it became a valid political opinion to deny reality and fight the messengers of that reality. In their view, reality was political, and we should just ignore COVID and act, and that would somehow produce a different reality where COVID didn't exist. A quote from the Bush administration, widely believed to be from Karl Rove, summarized this politicization of facts:

    "The aide said that guys like me were 'in what we call the reality-based community,' which he defined as people who 'believe that solutions emerge from your judicious study of discernible reality.' [...] 'That's not the way the world really works anymore,' he continued. 'We're an empire now, and when we act, we create our own reality. And while you're studying that reality—judiciously, as you will—we'll act again, creating other new realities, which you can study too, and that's how things will sort out. We're history's actors...and you, all of you, will be left to just study what we do'."

The movie "Don't Look Up" really nailed how we now seem to respond politically to factual, observable crises, and how non-political facts become "politicized."