This unfortunately doesnt cover it and when you read on in the comments to Rule 3.15 it stilll fails to cover this situation
3.15
No person shall be allowed on the playing field during a game except players and
coaches in uniform, managers, news photographers authorized by the home team,
umpires, officers of the law in uniform and watchmen or other employees of the home
club. In case of unintentional interference with play by any person herein authorized to be
on the playing field (except members of the team at bat who are participating in the game,
or a base coach, any of whom interfere with a fielder attempting to field a batted or thrown
ball; or an umpire) the ball is alive and in play. If the interference is intentional, the ball
shall be dead at the moment of the interference and the umpire shall impose such penalties
as in his opinion will nullify the act of interference.
Keep going. In the comments it then goes on to describe what to do if the base coach is involved - notwithstanding what the rule says.
And this is being hit with a throw, not interfering with the fielder as he attempts to field the ball.
base coach was not involved in the play it was the batter/runner that got hit by thrown ball after being put out on the catch