When you meet atton on peraguas u have a conversation with him about revan and if you say he is good then it will blow up but if you say he is bad then it is accessable.
"Fear attracts the fearful, the strong, the weak, the innocent, the corrupt. Fear, fear is my ally."
It's not that important, just a message describing in part what has happened to Revan since the end of the first Kotor (having played the first KotOR, this meant a lot to me). The point is, if you set Revan as good in that Atton conversation, the holocron message wouldn't apply to your story, so you're not missing out on anything.