A "step" would certainly be considered as accidental since no damage was intended.
A "stomp" on the other hand would be considered intentional with damage intended.
If you were to pay close attention to these football games you would likely see that every play in every game, somebody is getting stepped on........
While I'm certainly trying to defend Suh, there is nobody here that has been able to explain to me how Suh could possibly deliberately step on someone behind him without seeing him.