I agree with this actually. A 'partisan' judge would (to caricature) write down a legal argument and then vote in favour of the Republican platform regardless of what it said- that's very different from a Republican, non-partisan judge, who would write down a legal argument (which may be influenced by his Republican views) and then do exactly what he had written. Perhaps the effects are in many cases similar, but clearly one is infinitely preferable to the other
That's not really what is happening though. What is happening, exemplified by the cases of Heller and Citizen's United, is that the Republicans are deciding on an outcome, and then ignoring everything to reach that outcome. They ignore all precedent, they ignore statute, they ignore the letter and the spirit of the Constitution. They instead grab pieces of legal reasoning from anywhere necessary for making their case.