If you have a link, we can easily restore it. Without a link, we have to go searching for it.
To avoid having your thread disappear, avoid going back and editing the top post. That'll trigger Aksimet to give it another examination, and following rules literally no one understands (it's automated machine learning) may decide it's spam. If the post it doesn't like happens to be the first in a thread, then the whole thread goes away. So if, say, you want to add a link, do it in a new post rather than editing the original thread-starter.