Hello again Jake
You pose an interesting question. There a certainly several answers to your question but I will simply respond with the answer I believe a significant number of the Orthodox Bishops would give. The Patriarch who concelebrated with the Pope was in error and should never have agreed to do so. The majority of the Orthodox Patriarchs do not recognize the Pope as the legitimate Patriarch of Rome because of the heresy which the office of the Pope adheres to and practices....namely new innovations such as the immaculate conception of Mary, the Papal infallibility dogma, the addition of the filioque to the Nicene Creed, purgatory, and a host of others.
In addition, the present Pope has alluded to the possibility that the Virgin Mary should also be elevated to the status of Co-Redemptrix with Jesus Christ. If and when this heresy is finally declared as dogma you will witness the total apostascizing of the Roman Catholic Church. They will in effect cease to be Christian and should be treated as infidels much the same way as Muslims, Hindus, and Bhuddists.
If you do any serious study of the possibility of a reunification of the Orthodox and Roman Churches, you will soon realize that there are seemingly insurmountable issues which need to be addressed and resolved before a true communion can take place. A simple act of lifting the anathemas such as recently occurred will not resolve the problem. I believe it will only be able to take place if the Holy Spirit intervenes and changes the hearts of those hierarchs within the Roman Catholic Church to once again submit to the concensus of the collegial Bishops in regards to doctrine and oversight of the Church.
Thomas