In a community paranoid about the loss of political representation and influence in a country where demographic trends have pulled at that influence for decades, that interpretation stands on the grounds that the constitution – and the amendments implemented to it up to now in the Taef – is a sectarian one at its core; and the interpretation of any articles [in general, but for now specifically] pertaining to the selection of the community’s top post must take into account the spirit with [and circumstances under] which that document was drafted.
Those circumstances [and the spirit to which is alluded] mean [to those players above] that for an accord: negotiated to sow sectarian cohesion back together after nearly 20 years of violent sectarian conflict; in which the powers of the top Christian post were drastically weakened in favour of a Sunni Muslim post (that of the Prime Minister); and in which a Parliamentary Christian-to-Muslim ratio of 6-to-5 was reduced to one of 5-to-5; it would have been ludicrous and irresponsible for the representatives [of all the sects present] to assume that the Christians would also agree to the possibility of a Muslim [+1] election of the country’s Christian President (no matter the embedded vagueness that comes with having the Syrian regime “sponsor” the accord).
And while some would argue that the agreement could just as well have entailed a Christians [+1] vote, the historical fractionality of the community [as compared to the other communities], in addition to the community's respectively decreasing demographics and the intervening circumstances of the time-period in which the Accord was drafted, might prove otherwise.
Those circumstances outlined a bloody civil war in which members of the country's Christian community fought [and led] on either side of the political divide. While turf wars were not uncommon in any community, the broad strokes of the conflict [in its dying days, at least] defined a purely Christian anti-Syrian wing against a mixed Muslim-Christian pro-Syrian one. At the time Article 73 was (re-)written at the end of the war, the Christians were divided, just as they had been at the beginning of it.
And so, it is that sectarian-based interpretation of the Constitution and its articles surrounding the Presidency that is driving the positions of the Patriarch and those March 14th Christians openly declaring their support for a position that would otherwise be incompatible with their political stances.