Technically, it’s legal.
The rule was put in place for runners taking leads not directly in a straight line, but abused by bush league coaches to have a player run out in the outfield and “establish their base path” which is obviously in no way even in the right direction to 2B.. but they take advantage of the rule, so no need to get upset.
it’s Bush league no doubt. It’s used mostly by younger teams and to take advantage of younger skill level and cause a blunder to sneak the runner on third home. Teach your kids to defend it, and move on. I get a good laugh at coaches trying to pull these type of shenanigans.