You are misreading if you say the league is backing the officials here. They are NOT doing that. They are not, not backing them either. The rulemakers realize that many times what is seen on the field may not appear to be that bad which is why they put in the rule giving the league the "right" to take action afterwards. Why they thought they needed to do that is beyond me. Each league could develop their own policies for punishing misbehavior so putting it in the rulebook was really not needed.
All the league is doing here is saying they are not going to penalize this player beyond the penalty already given. Even if the player had been ejected, that would not mean he would be out the next game. So the league may tell the Referee behind closed doors that he should have ejected the guy but we will never know, nor is it really that important.
I will wait to see if this comes out on the CFO accountability video and get Mr Parry's take