Answer:
No! It is perfectly reasonable for an economist to donate money to the poor. The discussion in the text was referring to an illegitimate application of economic theory. Specifically, some people learn the "law of diminishing marginal utility" in standard economics courses, and then falsely conclude that a dollar confers less utility on a rich man than on a poor man. This talk is meaningless; economics says no such thing. Now if we want to justify charity on the grounds of moral obligation, that is consistent with economics. The only point here is that standard utility theory does not justify wealth redistribution the way many people think it does.