I don't talk about other matches with different refs.
This one is not the rudest ever elbow swing. Sergio was frustrated as he didn't feel fairly treated, yes.
His elbow is too high, yes. It should not happen in football, yes.
And you are spot on about the refereeing during the match. And consequently a yellow would have been okay here since he has allowed all the grabbing and holding before - against the rules in place. Poor ref all over.
Why should Sergio pay the bill all alone for such a poor ref performance?
Okay, because the FA can.