I see the issue itself as having a moral dimension but that does not translate reliably into one side being moral and the other not, nor into one side being more intelligent. It's clear that there is a hopeless impasse in the way people see the whole thing, both as individuals and as a social whole, and since the argument is essentially stalemated and the scenario itself so abstract and featureless that it loses meaning, I'm quite willing to stop being too serious and be accused of riffing.
I still think that, while this is the best way to look at it from outside - that is, as what the whole society should do - it's not really that simple if you're inside, where you must at least consider how other people are going to think and act. And that includes knowing that a possibly significant percentage of them will be thinking like EC, and a possibly significant number of the third-party-oops-we-got-Brexit sort will vote red as a gesture of protest or dissent, assuming enough others will vote blue so that they won't be held responsible. If you feel reasonably sure blue will lose by a margin you can't influence, then there's a "work from within" argument for joining the reds even if you are blue-inclined. If you feel reasonably sure that blue will win by a margin you can't influence, and then vote red just to be contrarian or to hedge your bets...well, ◊◊◊◊ you.
But all that said, yes, as a basic instruction for a society or a world in which such a scenario were to present itself, it is that simple. If you were appointed principal pundit or head oracle, to inform people of what they should do, then it is that simple. That's what they should do. Unfortunately they probably won't. Some of us won't be around to see the mess they make of it.