With mtgox, every customer is an investor. When bailing out a bank, however, the rationale is often to help out the people who cannot be blamed: the customers.

I'm still not claiming that bailing out I banks is a good thing, but the comparison you make is a small apples/oranges thing.

Except that it isn't. Hence why many smart people disagree on the issue.

The difference is meta-ethical. The TBTF argument is fundamentally a utilitarian one - it's saying, "This is distasteful, but we're going to do it anyway because we believe it will result in a better final outcome." The Libertarian take on the issue frames it in a fundamentally deontological light, as you have. It's concerned with the actions themselves, and doesn't even attempt to speculate on long-term practical consequences of any particular choice of action because they aren't relevant to the argument under that particular framing.

Which is fine, both are legitimate approaches to ethics. What bothers me is when the two camps start just talking past each other. Which is what seems to be happening when one makes a statement such as "the morally superior one should be relatively obvious" in this context. In terms of persuasiveness, it's reminiscent of the Verizon "Which one is bigger?" ad campaign - there's an attempt to get at something legitimate there, but it's overshadowed by a rhetorical approach that could make even the best argument in the world feel unpersuasive.

That said, this whole episode might serve as an interesting case in relation to many Libertarian talking points, such as the relative merits of many regulations covering savings & loan organizations in most countries.