I interpreted that quest as:
He wants to turn the Republic over to the Sith
He's not going to directly say, "Hey, let's join the Sith!", because that will fail
Instead, he's going to put forth a series of actions that he hopes will subvert the Republic until it is forced or tricked into joining the Sith
The document details his true plans about his upcoming proposals.
The LS option is the Lawful Neutral action - you really don't have any right taking his docs without a warrant.
The DS option is the Neutral Good action - you're breaking to the law, but exposing an evil plot.