I got the sense that this seems to be an old canard or misconception about ASD/HFA people - the corollary being that "they could control their manifestations if they really wanted to" - but have you ever been told that you "lack self-respect"?
I suspect that this mentality or harsh response may come about b/c neurotypical people generally don't want to believe that someone is unintentionally socio-emotionally "dumb" - because that's construed as [taboo] mental illness.
It could also be a subjective value judgement to the effect of "you haven't corrected these weird behaviours 'by now', ergo you lack self-respect." Or that it's something you should have shed earlier in childhood. Or that you didn't work on yourself enough or "try harder".
It could also be predicated on the expectation that you respect others in your interactions with them, and with our blundering it may appear as though we're insensitive, or aloof...and evokes the old adage "if you don't respect others, it shows you don't respect yourself" (and vice-versa). But perhaps this is a red herring.
The other more perverse example is when we're subject to bullying and there are peers watching (which has persisted into my early 20s, sorry to say) and you walk away and/or meekly say "yeah, I guess you're right" rather than getting into a physical confrontation (because who wants to end up in the hospital, or in a cell awaiting trial, right??!?) which we may think is the smart thing to do, since we already have a low opinion in the eyes of others and care little what they think of us at a certain point.
Paradoxically, in principle, it should really be the opposite: given someone with our struggles, maybe a lot of us have a great sense of self-respect in taking certain risks in trying to integrate themselves into social circles and what-not, instead of just lounging in their parents basement playing video games. Unfortunately, few see it that way.