Who knows how the ACA decision will come out, but a couple general points worth reiterating:
1. I'm surprised at how many people are surprised that judges are (at least sometimes) political actors, and not simply impartial arbiters of the law. Some of this outrage, from both sides, is feigned by people who know better; some of it appears to be genuine. The Supreme Court, no less than any other judicial body, is subject to political pressure: it's why Marbury v. Madison is decided as it is, it's why the Court didn't decide habeus corpus cases until after the Civil War, it's why the Court backed down after FDR's court-packing scheme, it's why Brown v. Board had to be argued three times. Legal realism, y'all.
2. The Supreme Court is not democratic. This is intentional. It is not a flaw. Democratic norms are all well and good, but in pure democracies people tend to occasionally make poor decisions, and so our government is filled with non-democratic pockets whose purposes are to do other things: in the Supreme Court's case, to protect rights and liberties and understandings of law that might otherwise be placed aside for temporary and inadvisable political reasons.
3. That judges are political actors does not compromise the value of their judgments, right or wrong. It's not inconceivable that people who hold an office might put aside their considered political opinions, or temper them, when deciding a case. And political arguments of expediency and legal arguments from principle are often hard to distinguish. To validate this, one would have to look at individual decisions, and conclude there was no plausible explanation for the views expressed therein but political argumentation. Which, I imagine, would be quite hard to do.