@Leftimies : Are you truly saying that you see some reason for France to take pains not to propose a homosexual as Ambassador to Vatican?
Or, for that matter, that Vatican has any reason not to accept one on grounds of homosexuality?
Sorry, but I hope you are kidding.
Its not my personal opinion on the matter, so there really is no reason to get worked up. It is a sort of realist viewpoint, I guess you could say. Let me explain. First, let me establish three essential points for the explanation:
(a) Vatican is, at its core, a theocratic monarchy established on the principles and teachings of traditional Christianity.
(b) Diplomacy is, in essence, negotiation, friendly relation-maintenance and deal-breaking between two countries.
(c) The Bible, can easily be read to be against homosexuality while lacking any explicit stands in defense of it.
Now, for France to choose a gay ambassador for Vatican (see: a) for upholding of diplomatic relations (see: b), when they knew
full well the, perhaps backwards, opinions of Vatican regarding his orientation (see: c) is broken logic which will result in ill outcome.
It is reality, it is politics. The reason why the ambassador got turned back was because the people at the Vatican, unsurprisingly, did not appreciate the gesture. The entire Vatican state exists solely as a state-representation of the Christian faith, and one could argue that if they did not uphold their own tenets, their whole state could be considered illegitimate, or at least utterly purposeless. They might not even believe in the religion, but for the sake of politics and the rhetoric, they really do not have choice.
Another known theocracy with stances against homosexuality is Iran, and I wouldn't consider it to be all that wise to send a gay ambassador there, either. You can work diplomacy to your own advantage the best when you are as neutral as possible; taking active stances on issues controversial to the other side (especially in the form of your diplomatic representation) is generally not a good idea and could represent a major hindrance to any bilateral diplomatic effort later on. If you want the relationship dynamic to be smooth and easy, rubbing something your 'friend' doesn't like in his face will work to the contrary.
I am quite surprised, if not shocked, that I had to explain this. Its common sense and more importantly, its how even the most basic of human relationships work.