People need to learn that there are consequences when you start changing laws. Red cards for denying clear goalscoring opportunities in any circumstances was fine imo. The change in the law, so that it cannot be both a pen and a red, is what has caused this confusion and why this incident is a red and a defender just sliding straight through the back of an attacker almost certainly wouldn't be.
They couldn't just change the law and make all pens for goalscoring opportunities yellows or else you'd have defenders just hauling forwards down when they're about to tap the ball into an empty net. They had to put the condition in that if you're not playing the ball then you can still be red carded. And this is a consequence of that.