Nice. I like your explanation much better than mine. Keeping in mind that Lucius knows very little at this point about what Harry is like — and that Harry is only eleven! — I guess it's reasonable for Lucius to assume that such an observation by a fellow student of Draco's would require some adult tutelage.
I just realised that I missed another very strong piece of evidence which immediately precedes Harry's statement: Draco states that Harry should meet Lucius - he is actually offering Harry privileged access to his father.
This strengthens my view that Harry has noted that Draco offers (multiple paths to) influence with or threat to Lucius.
(The HPMOR discussion thread after this one is here.)
The previous thread is over the 500-comment threshold, so let's start a new Harry Potter and the Methods of Rationality discussion thread. This is the place to discuss Eliezer Yudkowsky's Harry Potter fanfic and anything related to it. The latest chapter as of 09/09/2011 is Ch. 77.
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: one, two, three, four, five, six, seven, eight. The fanfiction.net author page is the central location for information about updates and links to HPMOR-related goodies, and AdeleneDawner has kept an archive of Author's Notes.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: