hes the ump with the best vantage point as to whether or not the batter offered at the pitch. The only better vantage point would be in the dugout but it would be weird for an ump to be in there.
He did clearly eff up that call and i don't know why, as an ump, you would have it in your brain to err on the side of calling it a swing if it means the end of the game...especially an elimination game. I would think if they are appealing a check swing you would want to be pretty damn sure before putting your fist in the air.
All that being said, I don't find it that terribly eggregious because it was 0-2 or 1-2 and there wasn't a RISP. if there was a RISP then yeah i'd be a lot more pissed about that call but realistically the giants were not going to win on wilmer's plate appearance. best case he gets a single. also wilmer was 0-17 lifetime against Max, so, statistically speaking it was probably headed for the same outcome.