If you only "move" the file, it's really only moved the given folder - i.e. it is still infected, of course. If you "move the file to Chest" - it would be something else. The files moved to chest are "hidden" (encrypted, in fact) - so that you cannot simply start them (even if you renamed them).
So, when you uninstalled avast, the content of the avast folder has been deleted - including the "moved" folder, containing the infected file. Therefore, you don't get the warning anymore.