No, I don’t think this is either unnuanced or simplistic. War is bad, period. Sometimes it is necessary, as the very last resort, but otherwise it is an unqualified bad. There is such a thing as just war theory, which was inspired, in the western tradition, by the virtue ethical approach of the ancient Romans. It’s hard to think of more than a couple of wars, historically, that would actually qualify as just.
As for the oil industry, it isn’t about its past merits, it’s about the current damage, which can be halted by progressively shifting out of oil-based approaches.