Undoubtedly the right decision, but I'd reserve 'disgusting' for a Roy Keane on Alf Inge Harland type challenge, where the player deliberately sets out to injure an opponent. Here you've got a debutant youngster getting carried away and making a wild lunge to win the ball, poor challenge which could have had serious consequences for the Millwall player, but don't think any malice in the attempt.
You've not mentioned Millwall's Jed Wallace's challenge in the same game. While it wasn't as bad as Baker-Richardson's, it was studs raised, making contact with an opponent, was Wallace fortunate that Mr Scott only produced a YC?