Was I correct to bench my U10 player who slide tackled two games in a row?

In our league at U10 slide tackles are absolutely not permitted and are an immediate foul. We had two games this weekend. In the first game this player slide tackled late and while the official didn't call a foul I knew it was wrong so I corrected my player sternly about it post game and made it known that it won't be tolerated. In our game the next day the hosting team's official canceled so I ended up officiating the game. Sure enough the same player, early in the second half of the game, went for a slide tackle again (which he called a slip.) I made true on my threat and benched him for the remainder of the game. Now his family is angry with me for how I treated him and he's threatening to quit soccer. Any advice on guiding this scenario? This is a promising athlete who I genuinely think can go as far as he wants in the sport if he just continues to have a drive for improvement.

My plan is to have a 1 on 1 with him at our next practice where I emphasize how far I think he can go and why I have high standards for his play (I've had him for 3 seasons + off season activities now.) It's my first time (shockingly) running into an angry parent/player in my 2 years now as a coach. Thoughts?