It only updates your PVP info. PVP data can only be gathered when the character is physically seen and/or targetted. At this point in time, only the person who takes a census is updated.
I used to process any target data you captured as well, but in an effort to stop bogus 'unguilded' entries from popping up, I have removed that for now. I might add it again in the future, who knows...
What about capturing any targetted data for members which are in your own guild? That way it wouldn't lose data and could still update members in your own guild (as you saw/targetted them)?