Board Thread:Support Requests - Getting Technical/@comment-27756776-20180923235312/@comment-24014422-20180924095410

I'm not sure about Forum threads, but with message wall threads it is not possible through any way to make deleted threads appear in "Special:DeletedContributions".

Threads seem to follow a different system when they are removed or deleted. The actions mentioned also do not get recorded in any logs. Any deleted thread and its offspring replies also still appear in one's actual contributions, unlike articles.

So, in short, you cannot have them appeared in the Special Page you want them to appear on nor the threads would be admin only reached unless you "delete" them so that no one can see them unless they have the right to restore threads (sysop).