If the President went to Justice Scalia's funeral, the right would rip him for politicizing the funeral, or would claim he's trying to steal the spotlight, or would make up some other basis for indignation.
When the President simply allows the funeral to be about the deceased (while paying his respects to the deceased in person in a more private way), the Right gets up in arms about his refusal to make a spectacle of the funeral.
The guy literally cannot win. I don't even particularly like this President, but to many it seems that the fact that this guy still bothers to breathe is simply too much.