In other words, when someone's expectations about a stated goal are wrong and the actual outcome will be something they personally consider undesirable.

Explaining to them why you believe they're making a mistake is justified. Interfering if they choose to continue anyway, not.

I strenuously disagree that inaction is ever morally neutral. Given an opportunity to intervene, choosing to do nothing is still a choice to allow the situation to continue. Passivity is no excuse to dodge moral responsibility for one's choices.

I begin to suspect that may be the root of our actual disagreement here.

I don't recognize a moral responsibility to take action to help others, only a moral responsibility not to take action to harm others. That may indeed be the root of our disagreement.

This is tangential to the original debate though, which is about forcing something on others against their will because you perceive it to be for the good of the collective.

Badly hung over, he doesn't show up to work the next day and is fired from his job.

I don't want to nitpick but if you are free to create a hypothetical example to support your case you should be able to do better than this. What kind of idiot employer would fire someone for missing one day of work? I understand you are trying to make a point that an individual's choices have impacts beyond himself but the weakness of your argument is reflected in the weakness of your example.

This probably ties back again to the root of our disagreement you identified earlier. Your hypothetical individual is not depriving society as a whole of anything because he doesn't owe them anything. People make many suboptimal choices but the benefits we accrue from the wise choices of others are not our god-given right. If we receive a boon due to the actions of others that is to be welcomed. It does not mean that we have a right to demand they labour for the good of the collective at all times.

Complicated? That's clear as day. People can either accept the vaccine or find another society to live in. Freeloading off of everyone else and objectively endangering those who are truly unable to participate is irresponsible, intolerable, reckless idiocy of staggering proportion.

I chose this example because I can recognize a somewhat coherent case for enforcing vaccinations. I still don't think the case is strong enough to justify compulsion. It's not something I have a great deal of interest in however so I haven't looked for a detailed breakdown of the actual risks imposed on those who are not able to be vaccinated. There would be a level at which I could be persuaded but I suspect the actual risk is far below that level. I'm somewhat agnostic on the related issue of whether parents should be allowed to make this decision for their children - I lean that way only because the alternative of allowing the government to make the decision is less palatable. A side benefit is that allowing parents to make the decision probably improves the gene pool to some extent.