Isn't this whole movie just an account given by some 'Jedi dude' who had his own opinion about Revan and what happened, just like Kreia had her own? It's not like 'I know everything and you have to listen to my words'
It's not like Revan himself is telling about his motives. It happens in 'Darth Bane: Path of Destruction'. Then you know that Revan fall to the Dark Side completely. (hint: Revan's holocron)