I don't think we can make that conclusion at all. Note my phrasing.
- "defense mechanisms"
- calloused shell"
- "burying any perceived vulnerability"
Perhaps a useful analogy here would be your own experience with autism. This has lifelong consequences for how your brain works, and it takes significant time and effort to overcome some of those challenges. As a fellow high-functioning autist, I've received extensive training on the arts of empathy, tact, body language, and so forth; and as a result I can pass for "normal" when properly motivated. But it's not intuitive and it's not easy; it never will be. Now, to the analogy part: trauma appears to produce lasting changes to the brain, which, naturally, have behavioral consequences. Depending on the exact person and situation, this can result in more aggressive behavior later in life. To a certain extent, Asuka may not be able to "help it", any more than you can "help" leaning toward dichotomous thinking. But due to mental plasticity, proclivity is not necessarily the same thing as destiny or inevitability.
I think that NGE is, to an extent, a stealth commentary upon the state of affairs in Japanese mental health at the time. Which, to put it bluntly, were not good; they made my own country look like a pinnacle of progressivism. As far as I can gather, you were expected to suffer in silence alone, lest you become a "burden" upon others; and if anyone learned about your illness, it would be implicitly deemed a moral failing on your part. NGE shows the disastrous consequences of broken souls hiding behind crumbling facades, in a world where therapy doesn't even seem to exist. So in a way, Asuka's problems are there to provide a lucid illustration of what can go wrong when some of the most basic human needs are neglected. Most of the characters act as cautionary tales in their own way.