Spam detection seems to work locally for threads.

The thread deletion concern seems valid, as does the suggestion that deleting a discussion page should be able to delete all its threads.

davemccabe wrote:

I am working on a proper and complete solution to deletion presently, so you don't need to worry about it, Werdna.

As for the more general point about using MW functions, you're right, we should strive to make LQT consistent with the rest of MW.

Generally using MediaWiki functions as opposed to home-grown solutions is something I've worked on over the last few days. The other two comments are separate issues, for which I will open separate reports.