The stem-cell veto and the Constitution

I am interested in people's reactions to this piece, from Jurist, by Professor Elizabeth Price Foley.  She contends that, because "[t]he Constitution, as interpreted by the U.S. Supreme Court for the last thirty-three years, does not recognize pre-viable embryos as 'human life'"; and because, given Casey and Roe, "under the Constitution of the United States, parental liberty trumps any interest government might have in protecting pre-viable human embryos"; it is therefore the case that "when President Bush justified the use of his veto power to prevent 'the taking of human life,' he was using Executive power to effectuate a personal moral view that is fundamentally antithetical to the law as declared by the Constitution and interpreted by the U.S. Supreme Court. He was defeating a legislative act – thwarting the will of 'We the People' – to pursue an agenda contrary to our declared Constitution."

Is this argument -- I hope I have stated it fairly -- persuasive, or even plausible?  Put aside, for now, doubts about whether the Roe line of cases in fact stands for a constitutional-law rule that pre-viable embryos are not "human life" (as opposed to a rule that, because such embryos are not "persons" protected by the Fourteenth Amendment, before viability, a woman's privacy and liberty interests outweigh whatever interests the state might have in protecting them).  Is it likely that the President's duty to “preserve, protect and defend the Constitution of the United States" precludes him from vetoing a bill for moral reasons that are in tension with the premises and implications of a particular line of Supreme Court decisions?  I would not have thought that even the strongest judicial-supremacy positions entailed such a result.