I’m not Catholic, but if I were, I’d say they should be excommunicated, though I think that would damn them to hell, as Catholics believe.
It’s a little more complicated than that, but I think they have have automatically excommunicated themselves.
That is not what Catholics believe regarding excommunication.
Excommunication of laypeople principally means that they are cut off from receiving the sacraments. It does not mean that the Church is condemning a person to hell. In fact, excommunication is intended to be a medicine to inspire people to repent and be reconciled to the Church. Once reconciled to the Church, that person may again receive the sacraments.
If an excommunicated person dies without being formally reconciled to the Church, he can be saved if he truly and sincerely repents all of his mortal sins before death.
Excommunication is a restriction of the reception of Sacraments for an individual Catholic who has repeatedly committed a public sin or deceptively taught a heresy as Catholic doctrine and repeatedly refused to correct it. Excommunication is always intended to be temporary and is primarily intended to be used as an encouragement to correct an overt public behavior that misleads large numbers of people about what the Church teaches. It is by no means an expulsion from the Church or even a permanent declaration. The root of the word is “communion.” Communion is the central Sacrament of Catholicism and excommunication generally means that you are restricted from receiving that Sacrament until you have corrected the issue. There are many forms of excommunication that are automatically imposed by certain actions by Catholics that can be removed very easily by simply receiving the Sacrament of Reconciliation. For instance, any Catholic who commits a mortal sin (which means all of them) has incurred a form of excommunication that can be lifted by going to confession. This is considered a normal routine for any serious practicing Catholic.