Of course anyone can clearly see there was no violent intent, or what the laws refer to as "excessive force or brutality" or, "in addition", deliberately striking an opponent on the head or face". However, you're just not allowed to put your hands around someone's neck, even if you're actually grabbing the collar around the neck.
VIOLENT CONDUCT
Violent conduct is when a player uses or attempts to use excessive force or brutality against an opponent when not challenging for the ball, or against a team-mate, team official, match official, spectator or any other person, regardless of whether contact is made.
In addition, a player who, when not challenging for the ball, deliberately strikes an opponent or any other person on the head or face with the hand or arm, is guilty of violent conduct unless the force used was negligible.
However, in light of what Casemiro was clearly doing, which was to defuse rather than inflame the situation, I can see the ban being limited to one match. We'll see.