Context and nuance are everything of course, and we don't know if President Sarkozy was simply making the normative statement that for the Lisbon Treaty to survive, it is necessary to have another Irish referendum, or that the Irish must (with all the undertones of compulsion) vote again; both would roughly be covered by "Il faut". I'm open-minded, though also aware that the latter is entirely possible.
(Also subject to interpretation are his remarks last week about the tradeoff between further enlargement and Lisbon. When he said that the Treaty issue must be "settled" before any more countries can join the EU, did he deliberately not stipulate that it should be approved?)
The wider problem is that many inside the Brussels beltway just don't get how serious the problem is. Someone terribly well-meaning invited me to join a Facebook group the other day whose description began: "EU should not be a hostage of 1 milion Irish who voted NO to the Lisbon Treaty." Well, too bad; it is - and had there been similar votes in other countries, I can easily think of half a dozen which would have produced a similar result. As I've said before, I rather feel that the drafters of the grand design have been asking the wrong questions.