I think they probably do understand these principles or at least the very basis of them as I do with animal rights but I put it aside as it gets in the way of my meat agenda.
While I'm inclined to agree with the rhetoric, it's important to understand that "not absolute" !== "not protected", and are constantly using tropes like fire in a theater as an excuse for banning insensitive speech and such.
A lot of it is willful, but if we keep believing the idea that our rights are fungible, then our rights will indeed become fungible. Every generation's erosion of civil liberties compounds to the new normal, which makes the next generation's erosion of civil liberties more possible, and in too many cases, even welcomed.
I think the problem with the current politics of fear is that it does seek to promote one absolute right -- the right to be safe from attack by bad people -- as more important than all the others. Of course, it is impossible to truly achieve that goal no matter what you sacrifice. But in the quest to do so, more balanced "greater good" philosophies developed over centuries of human civilisation, like preferring to die on your feet than live on your knees, or preferring to risk letting a guilty man go free rather than risk imprisoning an innocent one, or refusing to negotiate in the face of threats, can be cast aside all too easily. That's what is happening today.
And people wonder why Americans love guns so much...