mythcommflag depends on frontend?

I see the following in mythcommflag.log on my backend system:

mythcommflag[11668]: E CoreContext filtermanager.cpp:131 (FilterManager)
Filter dir '/usr/lib/mythtv/filters' doesn't exist?

apt-file search /usr/lib/mythtv/filters tells me that file is part of
the mythtv-frontend package.

Right now commercial flagging is not working for me, but I'm not sure if
this is the reason. But it seems odd to me that a backend function is
requesting a file that only exists in the frontend. What can I do about
this, short of installing mythtv-frontend on my backend-only system?

-Rob