My background is in educational science where we face similar dilemmas. In both fields I'd say there is no conflict between scientific rigor and political goals as long as you make your goals transparent.

The fact that you want to study economic processes because you want to e.g. better the live of the poor half of society does not mean you can't apply scientific principles. But the results will not necessarily be applicable for those who think a rising tide lifts all boats and therefore want to develop the economy in the interest of the upper class.

In fact I'd be suspicious if people claim to be unbiased in any field that even remotely has something to do with humans or society - it usually just means they either hide their interests, or aren't aware of their biases.