Had a similar situation last night in league play. Men's USSSA Class D league. 1 out, runner on 1st. Batter hits a pop fly to RCF or LCF (can't remember which one, but it was one of the two). Runner goes about 10 feet down the path to see if the fielder will catch it, which he does. Runner starts to walk back to 1st instead of "challenging" the thrower, but the thrower (who probably had a beer or two before the game) decides to throw anyway, throwing it pass the 1st baseman, and it hits the fence with the kind of roll that puts it over the fence and out of play.

I send the runner onto 3rd, defensive coach (who is also first baseman) comes up to me saying I was wrong. He starts saying the 1+1 stuff, and I said that's not even in the rules, plus told him, it's 2 bases from where the runner was at the time of the throw, which is 1st base. He didn't like it, and didn't say more.