“Spurious” sources and commentary from the 5th. - 8th. cen. versus Paul's clear statement? Not what I could reasonably call “evidence in favor”
Since Paul's words were applicable to others besides Mary why would he single her out, living or dead?
By what objective measure can the passage you quoted be considered an argument against the Assumption of Mary, since there is no direct reference? Has any reliable authority interpreted this scripture to be applicable to the Assumption of Mary? I do not see it.