How could I spell out Pope Francis’s "Who am I to judge?" remark on gay priests?

A New York Times article from July 29, 2013 introduced Pope Francis’s remark on gay priests which he made aboard the papal airplane on the way back from his first foreign trip, to Brazil.

“If someone is gay and he searches for the Lord and has good will, who
am I to judge?” Francis told reporters, speaking in Italian but using
the English word “gay.”

Pope said this in Italian. Is "Who am I to judge?" a right translation? Couldn’t it be "Whom am I to judge?" or "Who am I if I were to judge?" How could I spell out this phrase?

P.S. Ross Douthat provided full text of Pope’s remark including “Who am I to judge.” in NYT Jul 30 issue:

“A gay person who is seeking God, who is of good will – well, who am I
to judge him? The Catechism of the Catholic Church explains this very
well. It says one must not marginalize these persons, they must be
integrated into society. The problem isn’t this orientation — we must
be like brothers and sisters. The problem is something else, the
problem is lobbying either for this orientation or a political lobby
or a Masonic lobby.”

I was under the impression that “Who am I to judge” was just a clip from a short Q&A between the pope and reporters aboard the papal plane, but it was a part of a well-structured discourse. It seems I made a premature post, without checking the full context of Pope’s message. Now the meaning is pretty clear to me.