Organizations have rules-THe RC had every right to excommunicate him for breaking the rules and encouraging others to break them
That’s actually not a correct interpretation of the happening.
The Church of Christ - as you certainly know from Acts and in general from the New Testaments - has authority to inflict certain penalties for the spiritual health of its children. For a shepherd, the penalties go as far as laicization - the removal of the authority to exercise his pastoral ministry.
Excommunication, however, is not imposed to someone who breaks a rule. Excommunication is a medicinal penalty which is given for the benefit of someone whose salvation is gravely at risk. The Church, our Mother, can give no greater a warning to her children than excommunication - which is the mere statement that until the person does not repent from his scandalous and habitual state of sin, he may not partake of the Body and Blood of Our Lord Jesus Christ, as this would be the worst sacrilege a man could commit, and may not benefit from the Sacraments which require us to be in the state of grace.
Every excommunicated person has the right to receive immediate absolution if he repents from his sin, and excommunication - as I said - is reserved for the gravest sins, which truly place a soul in grave risk.
To encourage others to break rules also leads to some sort of canonical penalty. To lead others to grave sin, even unto mortal sin, is a sin of the gravest kind that no canonical penalty is fit to punish. Under such circumstances, the Church can only cry out with the most sorrowful of its motherly admonitions, hoping that this may suffice to shake her child’s heart to tears and lead him back.
Let us pray for this priest of Jesus Christ, that he may be filled with understanding and true contrition, returning in humble submission to the bosom of the Church, for God’s greater glory and the salvation of many souls. This may be impossible for men, but nothing is impossible for God.