As a special child  of the yellow-eyed Demon, he was completely unaffected by the powers of other said special children.  Before he even drank the plasma, this immunity was in effect, which is why he wasn't susceptible to mind control and the Croatoan Virus.

The settlers, who arrived in 1587, disappeared in 1590, leaving behind only two clues: the words "Croatoan" carved into a fort's gatepost and "Cro" etched into a tree. Theories about the disappearance have ranged from an annihilating disease to a violent rampage by local Native American tribes.