Magic fucking blood? Seriously!?
How is that more ridiculous than a magic torpedo that creates entire terraformed planets out of thin air and regenerates Spock? Your sense of perspective is totally off.
How is the regenerative properties of the blood at all inconsistent with what we have seen in the Augments arc on Enterprise
? There, Augment DNA performed all kinds of miraculous feats like drastically changing the bone structure of Klingons in minutes and was originally intended to increase their strength, speed, stamina, and survivability. So, having some regenerative capability, especially with cells damaged by radiation as opposed to someone being blown apart by a phaser, seems plausible in Treknological terms. They're not Wolverine level regenerative, and can still be killed, but they can recover from disease, radiation, and things that leave the body mostly intact.