I agree that I have indulged in a bit of a rhetorical excess above. What I had in mind is primarily welfare economics -- as I indicated in another comment, I think it's quite evident that this particular kind of formalized utilitarianism is regularly used to construct arguments for various ideological positions that are seemingly rigorous but in fact clearly rationalizations.

I also agree that non-utilitarian theories of ethics are fertile grounds for rationalizations too. I merely wanted to emphasize that given all the utilitarian rationalizations being thrown around, the idea of utilitarian thinking being somehow generally less prone to rationalizations is a non-starter, under any reasonable definitions of these terms.

As for the issues of charity, I think they are also more complicated than they seem, but this is a quite complex topic in its own right, which unfortunately I don't have the time to address right now. I do agree that this area can be seen as a partial counterexample to my general thesis about uselessness of utilitarianism. (But less so than the strong proponents of utilitarian charity commonly claim.)