Casemiro could not have been given a red card because the referee played an advantage on his tackle, and giving a yellow card would have been wrong.
Unless you think every sliding tackle should be a yellow card which has no basis in the laws of the game either.
I am a level 2 referee, I am very familiar with the laws, but thank you for the links and your views!
The referee has two choices, play advantage that would lead to a goalscoring opportunity, or stop play and award a direct free-kick. If he felt the challenge was deserving of a second yellow card, he would assess whether the continuing attack was - in his view - a goalscoring opportunity. He deemed it was, so a second yellow card wasn’t given.
However; this is the law in practice, not on paper. Two yellow cards, for instance, can be given in the same phase of play for two separate yellow card offences. The referee would immediately stop play and produce both cards, then a red.
In this case, in my view, the referee didn’t afford an appropriate opportunity of goalscoring to not award a free-kick and a second yellow card.
The Antony incident is beyond question.