he was convinced and "infected", his mind told him to live and that the flood was going to kill him if he didn't do what the grave mind wanted him to do.

and i know "perfect" is misleading but thats what they really are called. look at skynet from the terminator, that is by definiton a perfect A.I., it was not good, it was corrupt by a virus, it did everything a perfect A.I. could worked perfectly like it should and was purely programed.

a person can go corrupt, anything sentient thing can go corrupt. A perfect A.I. and a smart A.I. are very close, and have mostly the same properties, the main difference is the perfects are programmed, smart are copies of neural pathways of a living human and this causes them to have no limits to how fast and how much they learn and , like a human, if you learn to much to fast you do go insane. and yes it has happened multiple time through out history.

EDIT** 

Also a person can go "rampant" and is no less of  person. besides  Bias's "rampancy" does not follow Smart A.I.'s rampancy. A smart A.I. believes its is god like and all powerful, Bias just switch sides, he never thought he was a god