Some naughty boy walking over a pond distributing his blood without a medical assay is no basis for a system of ethics. Supreme moral authority derives from a mandate from the masses, not from some farcical reverse-vampire ceremony.

More seriously, the OT Ten Commandments come with a whole bunch of asterisks — Thou Shalt Not Kill (except for war and executing criminals) — and even in the NT, when Christianity first popped into existence a number of the new converts immediately committed suicide right after baptism so that they would get into heaven with all their sins absolved and no chance of, e.g., dying immediately after an unwanted adultery boner [Matt 5:28].