DeCastro's actions were about the best you could ask for in that whole mess. He basically grabbed Garrett, threw him to the ground and put him in timeout by laying on him.
And it wouldn't have even gotten that far if Rudolph doesn't come charging in. DeCastro had Garrett wrapped up and walked back away from it. He didn't throw him to the ground until Rudolph and Pouncey came charging in and threw him and Garrett off balance. IMO DeCastro is the only one in the dust-up who shouldn't be disciplined, which means he's probably looking at a six figure fine and a two game suspension.