No, Honorius was not a monothelite. He was defended by no less that St. Maximus the Confessor against the accusations of the heretics. Would you then claim Maximus is a heretic for defending Honorius?
Honorius’ fault was that he followed Sergius’ (Patriarch of Constantinople) suggestion for a rule of silence - which thereby allowed heresy to flourish alongside orthodoxy while the heretics sought to supplant it. Honorius’ ‘heresy’ was that his negligent inaction, i.e., not teaching, had the effect of favoring the heresy.
Pope St. Agatho’s letter to the Sixth Ecumenical Council asserted the orthodoxy of all his predecessors - thus, by implication, Honorius as well. The Council explicitly accepted the letter and indicated its acts were in accordance with it, and anathematized those who rejected it. Therefore, logically, in accepting Agatho’s letter, the council accepted the orthodoxy of Honorius, but yet could still fault his part in the spread of heresy through negligence. Such was the tone of Pope Leo II take on Honorius as well.
http://www.catholicculture.org/culture/library/view.cfm?id=3301&repos=1&subrepos=0&searchid=1445229
The East at various times in history accepted the papal claims, such as at Florence, and in more ancient times, for example, the Eastern bishops had explicitly accepted and subscribed to the Formula of Hormisdas. So, I must beg to differ, with all due respect; it was rather our friends of the East who left communion with the Catholic Church, founded by our Lord upon the rock. They accepted the primacy at Florence, and if that be not enough, they had explicitly accepted and subscribed to the Formula of Hormisdas in the 6th century. As well, they had accepted Agatho’s letter (mentioned above) which asserted mainy of the same points, such as the Apostolic See of Rome remaining free from error.
But as the author of evil, who, in the beginning, availed himself of the aid of the serpent, and by it brought the poison of death upon the human race, has not desisted, but in like manner now, having found suitable instruments for working out his will (we mean Theodorus, who was Bishop of Pharan, Sergius, Pyrrhus, Paul and Peter, who were Archbishops of this royal city, and moreover, Honorius who was Pope of the elder Rome, Cyrus Bishop of Alexandria, Macarius who was lately bishop of Antioch, and Stephen his disciple), has actively employed them in raising up for the whole Church the stumbling-blocks of one will and one operation in the two natures of Christ our true God, one of the Holy Trinity; thus disseminating, in novel terms, amongst the orthodox people, an heresy similar to the mad and wicked doctrine of the impious Apollinaris, Severus, and Themistius, and endeavouring craftily to destroy the perfection of the incarnation of the same our Lord Jesus Christ, our God, by blasphemously representing his flesh endowed with a rational soul as devoid of will or operation.Of course, earlier there was much simpler:
To Theodore of Pharan, the heretic, anathema! To Sergius, the heretic, anathema! To Cyrus, the heretic, anathema! To Honorius, the heretic, anathema!...following the polychronia to the Patriarchs of Rome, Constantinople, and Antioch and to the council and the senate. (Quite the opposite of "accept[ing] the orthodoxy of Honorius.")
You would have us believe that the Harps of the Spirit erred in making these declarations, and this despite your church still giving lip-service to the authority of the Seven Holy Ecumenical Councils which we Orthodox also recognize. (Search your recently issued Catechism for references to the authority of the Ecumenical Councils -- even with your theory that a papal assent is needed for a council to have ecumenical authority, is there any doubt, given the content of the Papal oath from the 8th to the 11th century, that Rome assented to the acts of the Sixth?)