We ought to add a poll to this to see how many people actually thought the FA would do anything other than go through the motions to back the referee, they've shown time and again that that they lack any kind of backbone and will always cherry pick the easy option of fining a manager or player who has the audacity to actual ask for an explanation on anything (see Jose's I'd rather give money to charity than the FA comment).
I doubt many are surprised they did nothing, just more its a high profile case and expressing dislike of how utterly incompetent they are.
Arguably the best player in the league has suffered a season ending, potentially career altering injury via a reckless action and there was 0 punishment for it.