See my reply #23. It’s because of the difference between being a public figure publicly doing something sinful and encouraging others to do the same, and a private individual who shouldn’t go to Communion until he repents. He is self-excommunicated, but does not at present need public excommunication as a disciplinary matter, whereas the politician does because he is publicly flouting the law of the Church and encouraging others to do the same.
Then it is political, because the Church is singling out politicians and not ordinary people or other celebrities. And it wouldn't surprise me at all if the Democrats retaliated by threatening the Church's tax exempt status.