Mine said it was not smaller than a quarter. Those are some massive blueberries.

This is the way I'd understand it as well, and you explained it very clearly imo.

Single solve times have a lot of random variance, that could just be a random cube pattern that allowed him to skip several steps when solving. The average dips slightly at that point, but not below the beginning average

That isn't what I was saying. The Ballmer Peak specifically shows that performance at the peak is better than when completely sober. In OP's case, performance was only slightly better than the % above and below it, but still significantly worse than at 0

That's exactly what it shows, 0 BAC has a lower performance level than at ~0.14

The whole thing about the ballmer peak though is that performance is higher than when completely sober

Doesn't this show the opposite? He pretty consistently gets worse the higher the alcohol content