Uraeus, correct me if I am wrong but as far as I was aware Launchpad is not released software i.e. no one but Canonical uses it. Therefore IMHO there isn’t really a big issue about whether its source code should be released or not, since there is no one actually running it to take advantage of that. This assertion of course only follows if you believe that the main point of Free software is to empower the people running it, and not simply to share coding techniques.
If Canonical were to package Launchpad as a general purpose issue tracker, support tool etc. and other people were to start using it then yes I believe it would be extremely important for the source to be available, but as it stands I see it as an internal project and piece of infrastructure. Freely distributing its sources may enable faster improvements to Launchpad itself, but that would probably be hard work for someone outside Canonical and people inside presumably have access to its source anyway.