Hmm, some suggestions considering other people may want some custom changes to this:
1. Instead of usergroups to deny, you could keep usergroups allowed as there might be a lot of usergroups on the forum.
2. Make delete time a text box and instead allow users to specify custom time.
However, if I were to use this, I could do this changes easily due to plugin knowledge but other's might be looking for above two similar options.
Anyways, it's upon you to decide. Nonetheless, nice and one of the most requested plugin.