It isn't inevitable. There's a trivial demonstration that censorship self-censorship don't form necessarily form a collective downward spiral: There are societies that at one point had much heavier censorship and now don't. That's not easily made consistent with your claim.

I am claiming that this road leads to totalitarianism. That is not the same as claiming that the road is one way with no exits and no U-turns. If I thought otherwise there would be little point in me expressing my concerns. As long as society keeps its foot on the pedal and fails to realize it is heading in the wrong direction however that is where it will end up. Inevitably.

(Incidentally, generalization from fictional evidence also comes up here).

This is not generalizing from fictional evidence. It is using a literary quote to express an idea more eloquently than I can myself. Since the book can be seen as a parable illustrating the same concerns I am emphasizing I believe it is quite appropriate to quote from it. I am not using the fictional story as proof of my claim, I am quoting it to elaborate on what it is I am claiming.