Close Threads Automatically is the ideal product to eliminate the bumping of older threads.
Threads are not closed in the database, they appear as if they were closed. So, if you deactivate or uninstall the mod, threads appear as open again.
Note: Threads that are marked as closed by this mod via the Auto Close After X Replies setting, can not be reopened due to the fact that they have reached the max replies you set. Only way to re open them is to increase the reply limit or disable that feature.