The tag is present in Lintian version 2.104.234. That is the most recent version we know about.
/etc/init.d script specifies the S runlevel in
Default-Stop in its LSB keyword section. The S runlevel is not a real
runlevel and is only used during boot. There is no way to switch to it
and hence no use for stop scripts for it, so S should be removed from