This is similar to a issue that has come up often (and agin recently) on our boards, which I hope UBBDev might help with. That is a hack to remove the topic starter's ability to delete their initial post (thus deleting the entire thread) after someone has replied to it.
Despite all attempts to dissuade such, we invariably have people who, when they are unhappy with the way their topic is going, simply delete the thread. It is commonly felt among our staff and members that this is a real injustice, as no members should arbitrarily have the ability to edit/remove anything but their own words (with the exception of Admins and Mods, but that's different