About contemporary "liberalism" as an ideology: to an extent it seems to go into deliberate "we're not being ideological!" style expressions, becoming practically a nervous tick. Though not only is it an ideology, it could be argued everyone is ideological in some form. You don't have to say "this is an ideology" for an approach to political questions to be one, ideology doesn't have to announce itself upon entry to a room. Which makes the loudly pseudo-non-ideological stance of some progs ring even louder.
As for libertarianism as "infantile liberal democracy", if by this you mean a nod to how despite liberalism's corruption into just the shrunken left hand of the same general "shut up and trust the ruling elite" stance that always lurks, every once in awhile a prog might suggest that the correct response of government to something just may be no response at all, you have a point. That said, such moments are few and far between for a reason. Don't want to sound like they're saying people have less control over their lives than they should as a general principle, as that would be Ideological & thus assumed to be wrong.
But this...hoo boy:
[...]the total state is never anything more or less than the manifold result of countless reasonable calculations of desirable degree of concessions of pure autonomy or of unlimited negative freedom. If libertarianism is still libertarianism under reasonable calculation of concessions, and everyone agrees out of calculation of self-interest to the totalitarian state, then the totalitarian state is also the libertarian state.
Sounds like you're equating the actual formation of the total state with the aggregate choices of the populace as a whole (much as the snarkier form of progressive pointed at the near collapse of finance due to Capital Paradox and screamed "free market at work!"). This despite the practical root being that within the state the self-interest of some people always matter way more than others, and the dividing line between driving the steamroller and being the awaiting human pancake has nothing to do with what most defenders of such a system say it does.