It's a really difficult situation. I think I might have acted as you did; but honestly, I think it might have been better to let it go when he wasn't put forward for county (i.e. discourage his teacher from taking it further). Judgments of this kind often seem unfair to people who lose out by them. Sometimes they really are unfair (not necessarily through malice); sometimes, people who lose out simply lack understanding of what they didn't do right; sometimes the judgment involves so much subjectivity that there really isn't answer; of course these aren't really alternatives, it's a spectrum.
As you've discovered, fighting a decision when you consider it unfair can have a downside even if you are right and even if you succeed (and what you experienced is far from the worst that could happen; here one assumes this was an isolated unpleasantness, but imagine a teacher from the school mentioned Wolf's name in a context of "imagine what this pushy mother did" to someone who remembers it later when you need a favour from them... I mean, here's hoping this is balanced by the possibility that someone remembers Wolf's great science fair entry, but ykwim: there are risks).
What I think might have been a more prudent path would have been to say to Wolf that you're surprised too that he didn't get put forward, and that you don't understand it either on the basis of the rubric, and encourage him to ask politely for feedback on what he could do better another time. And then, if still convinced that there was unfairness, absolutely avoid entering via that school in future!
I really would run a mile from telling Wolf that he didn't get put forward because the committee favoured their own children. It seems vanishingly unlikely that they consciously did so; far more likely, they had a collective view, different from yours and Wolf's, of what constituted a good entry, which had been established among them and which therefore their children met and Wolf didn't. Since Wolf did better at the county fair than some of their children, it looks as though their collective view didn't coincide with what the people judging there were looking for, but this doesn't imply that the committee at school level were being dishonest. Frankly I don't think assuming dishonesty in other people where there isn't absolutely cast-iron evidence is a thing to encourage. Cockup is really a lot more common than conspiracy, and in any case, assuming that other people are often incompetent is less damaging to the psyche than assuming that they are often malicious ;-)
