Much less likely? That would require that such drafting be more likely on bridges than elesewhere

The problem induced by pushing the fat guy off is that people don't know which zones now count as "sacrificial lamb" zones (because of the bizarreness of the deviation from social norms), except that bridges over densely-populated trolley tracks are one of them, so I think the resulting world meets this criterion.

one is more likely to find oneself one of the million saved than the one person sacrificing, so most everyone should agree to a policy that those in positions to offer incredible help be drafted.

But people are already choosing risk profiles that, under present social norms, cause them to die when near tracks that have an errant trolley coming, so it's not clear why they'd make tradeoffs (giving up other things they value) for greater near-trolley safety, and thus not clear why they'd prefer this at all.

In this case, the cost (borne by everyone in the area, not just people near tracks) is that they have to re-organize their lives around choosing routes that avoid sacrificial lamb zones. But -- by the scenario's stipulation -- people aren't currently choosing to bear the additional cost to be on the safer bridge rather than the dangerous track. (If they were, the scenario would involve millions crossing the bridge and few near the track.) What they are choosing is to bear the risk of death because of the convenience it affords.

And because the option of pushing someone off the track tells people, "Okay, you have to be a lot more risk averse to get your current level of risk", they're forced to pay more for the same safety.

You're allowed to say "X is the action I would want to take, but I wouldn't be able to"

I don't think this statement is logically consistent. Unless you're restrained by some outside force, if you don't do something, that means you didn't want to do it. You might hypothesize that you would have wanted it within some counterfactual scenario, but given the actual circumstances, you didn't want it.

The only way out of this is if we dispense with the concept of humans as individual agents altogether, and analyze various modules, circuits, and states in each single human brain as distinct entities that might be struggling against each other. This might make sense, but it breaks down the models of pretty much all standard ethical theories, utilitarian and otherwise, which invariably treat humans as unified individuals.

But regardless of that, do you accept the possibility that at least in some cases, bullet-biting on moral questions might be the consequence of a failure of imagination, not exceptional logical insight?

It's more complicated than that. Most people would say that there are imaginable situations where a certain course of action is right, but they'd be strongly tempted to act differently out of base motives. For example, if you ask a typical person whether it would be right to gain a large amount of money by some sort of cheating, assuming you know for sure there won't be any negative consequences, they'll immediately understand that the question is about what's normatively right, not how they'd be tempted to act. Some very sincere people would probably admit that they might yield to the temptation, even though they consider it wrong.

Now, imagine you're introduced to someone who had the opportunity to cheat a business partner for a million dollars with zero risk of repercussions, but flat-out refused to do so out of sheer moral fiber. You'll immediately perceive this person as trustworthy and desirable to deal with -- a man who acts according to high principles, not base passion and instinct. In contrast, you'd shun and despise him if you heard he'd acted otherwise.

However, let's now compare that with the extreme fat man problem (where you'd have to cut the fat man's throat to avert some greater loss of life). Imagine you're introduced to someone who was faced with it and who slit the fat man's throat without blinking. Would you feel warm and fuzzy about this person? Would any of the bullet-biting utilitarians fail to be profoundly creeped out just by the knowledge that they are standing next to someone who actually acted like that -- even though they'd all defend (nay, prescribe!) his course of action relentlessly when philosophizing? Moreover, I would again bet dollars to donuts that our genteel utilitarians would be much less creeped out by someone who couldn't bring himself to butcher the fat man.

When I think about this, I honestly can't but detect severe short-sightedness in moral bullet-biters.

I can believe that a neurotypical person would be more likely to imagine themselves doing the actual killing, while someone on the AS would be more likely to stay with the abstract problem.

You can keep all of them if you're okay saying that sometimes there are only immoral choices (or at least no moral ones) and that sometimes the action we ought to take is under-determined by our moral intuitions.

Autism in general affects four times as many men than women in the general population;

Does this statistic refer only to severe cases of autism that are likely to be noticed and diagnosed whenever they occur, or also to the milder, high-functioning autism spectrum disorders? Because if the latter, I would expect that mildly autistic men are much more likely to be noticed as weird and dysfunctional than women, so this might account for at least a part of the discrepancy in the rate of diagnosis.

The explanation for the greater public prominence (and presumably social acumen) of female autistics is probably similar. In most situations, it's probably harder for autistic men than women to avoid coming off as creepy or ridiculous.

Are the words "women" and "men" reversed in your opening sentence?

Does "autism bloggers" mean "people who blog specifically about autism"?

If so, it might be instructive to check how many bloggers in other subjects also happen to have autism. It might be dificult to verify but the blogosphere is large enough to dig up a usefully-sized sample and disentangle to some degree the autism-blogging link.