I think it's a shame the way this thread came to a rather abrupt halt. Regardless, I think Wyatt made a good point:
The only difference between the other Bishops and the Pope is that the Pope's headship is on a worldwide level. That still doesn't negate Christ's headship because the Pope is the head of the Church militant in the present (i.e. the Catholic Church as it exists right now on Earth). Christ is the absolute head of the Church in all times and places...not to mention the fact that, without Christ, there would be no point in a Church at all, since the Church's sole mission is to spread the gospel of Christ.
I would be interested to hear what Orthodox have to say to this argument.
There is only one bishop for them, the one in the Vatican. All others are just his acolytes.
This is a representation of the Council of Nicea in the Sistine Chapel:
and an icon of the same
In the bottom, the Gospel Book (as the accounts tell us) stands in the center, with the altar looming behind. In the top, Hosios of Cordova (made into the legate of Pope St. Sylvester; in fact he was the personal friend of the Sainted Emperor Constantine, and it is not clear if he precided) looms in the center, the Gospel nothing more than his footstool.
Christ's Church has His Apostolic episcopate to lead it, we don't need a super bishop for a head. The arrogance of that heresy to redefine the Catholic Church as communion with him, and otherwise crush the whole of the Church into the singularity of the papacy underlines that fact.
So, despite all the disclaimers, the supreme pontiff negates Christ's headship and all the other bishops.