Yes, I come across this "automatic" excommunication frequently.
It is a convenient excuse, but that's all it is.
A Catholic who receives communion from the hands of his own bishop, or the bishop's representative, is, by a public act of duly appointed authority, a Catholic in good standing, imaginary excommunication notwithstanding.
No, a bishop or priest who does those things is disobeying his superiors. The Catholic politician is still excomunicated.