Firstly, let me clarify, - I don’t dispute that the Orthodox have valid orders or sacraments, however this is not what is formally meant by the the term Apostolic Succession, at least not in the Traditional sense. Materially, if you want, we can say they have 'Apostolic Succession, but formally this term always implied a unity with the See of Peter. All I am doing is reminder the reader of this distinction.
“There may be also other societies which glory in the name of Christ; there may even be some which are governed by bishops claiming apostolic succession; but they do not have the Chair of Peter, on whom Christ founded the Church. Therefore they do not belong to the household of Christ; they do not follow him to whom Christ entrusted the feeding of His lambs and of His sheep; and so they do not belong to the flock of Christ.” - Dogmatic Theology, , Christ’s Church, by Monsignor G. Van Noort, S.T.D.,
The Catechism of the Council of Trent implies the same point saying:
“That all, therefore, might know which was the Catholic Church, the Fathers, guided by the Spirit of God, added to the Creed the word Apostolic. For the Holy Ghost, who presides over the Church, governs her by no other ministers than those of Apostolic succession.”- Catechism of the Council of Trent.
As to trying to nullify the words of Fr. Rumble by merely appealing to the ecumenical movement, which you seem to want to use as some sort of magic wand to change reality, well that doesn’t work. Truth doesn’t change because someone merely wishes it away by some words of ecumenism, regardless of who or what are at the source of those words. The Orthodox still hold to heretical views which are directly opposed to Catholic teaching. They are heretics and Schismatics in the true and full sense of the word.
Cardinal A. Ottaviani warned against this false ecumenism which was being promoted after the Second Vatican Council. His text is on the Vatican website words worth pondering: