Comment 1 for bug 436039

So it's already explicitly doing this:

    #if we're root, try to run as a user instead
    if [ "$USER" = "root" ] && getent passwd nobody 1>/dev/null && su nobody -c "/bin/true" 1>/dev/null; then
        the_make_command="su nobody -c \"$the_make_command\""
        chmod +x $dkms_tree/$module/$module_version/build
        chown -R nobody $dkms_tree/$module/$module_version/build
    fi

How could that be failing? What about your situation is different?