Hello,
according to the archive, modules_s/*radius modules were kept because of duplicate and incompatible auth modules at the time there was an attempt to remove them: - http://lists.sip-router.org/pipermail/sr-users/2010-June/064318.html
Now there is a single auth modules, thus I guess the modules_s/*radius can be moved to obsolete.
If anyone has different opinion, reply with the arguments here.
Cheers, Daniel