If you read the comments made by different people on these forums, you will see that the results are mixed: some claim that the list is correct, while others notice people who are not active on Facebook, or even dead (!) in some cases.
My recommendations is to NOT believe in this claim. But since this is not harmful in any way compared with the apps we reviewed on this website, it doesn't hurt to go through your "initialchatfriendslist" and see who is there. You might even find out something new when you open a profile of a friend who you didn't check in a long time (moving to another country, getting married etc).
Happy stalking! :)