Based upon the fact that this was submitted to /r/science, I would guess that economics is a science if and only if it supports the political goals of the speaker.
(This is not, of course, to say that the article linked to is wrong. Indeed, it seems entirely plausible to me that the phenomenon it describes is real. Monarchs were not renowned for their generosity, the welfare state - or its precursors - is/were not about redistribution, and in general it seems likely that higher segregation by income will lead to lower social cohesion and trust, which are likely to play a large role in determining how generous people are. Or indeed, perhaps higher inequality means that it's harder for rich people to comprehend that there are other people who are considerably worse off than they are).