Looking into the issue you described...
OK, based on my initial research into this issue, and I could be wrong... I am leaning towards calling this a quirk in how the new "spam diff" works, which is a new feature in 1.17 or 1.18 of mediawiki. When it is showing you all those lines that it wants to remove, it is on the spam protection page, right? So it is not actually erasing stuff. It just looks like it wants to erase stuff. But this may be a quirk in my spam code with the new mediawiki feature.
So quick summary - I think the wiki is safe, unless you actually *see* the wiki erase lots of content like the spam protection page is making you think it wants to do. I think I just need to fix the output of the spam protection page.
If you actually see data being destroyed, let me know. But even then, the wiki has history. So don't be afraid of editing and don't be scared by the spam protection warning at this time.