stararmy The file action.php
explicitly says GPL 2. Further, as this is based on DokuWiki, it must be compatible with GPL 2. Therefore, there shouldn't be any problem with forking this plugin.
For some reason (he never wrote me why afaik) @lupo49 granted me write permissions on his repositories. I therefore could merge this pull request. However, as I do not have the time to maintain this plugin I would prefer if you could just fork the plugin and apply the pull request there. I would strongly suggest, though, that you do not rename the plugin to enforcesummary2. This will just confuse users and if the old plugin is not maintained anymore (which I suspect, attempts to contact him because of a similar situation with the cspheaders plugin failed, see here), keeping the old name reserved has no value imho.