User blog comment:Rrinderknecht/Season 2 Episode 8, Finn, Lincoln and the 18/@comment-26564154-20151124160010

If you can recall he was surrounded by Octavia, Abby & Kane when he made those comments, and although he was recovering for being on the drug he was lucid and of sound mind when he made said comments. Any of the 3 individuals would've brought him up to speed on past events, since they were in the room consulting him on how to deal with the Commander over Finn's actions.