OGS uses the rating to calculate the number of handicap stones, for several pairing modes in tournaments, to find players of equal strength in quick match finder and limit the range in witch we can challenge other players for ranked games.
This gives me the impression that the rating on OGS is supposed to reflect the player’s strength.
If we introduce an asymmetrical rule like the proposed win/annul but never lose, we would possibly disturb the ratings of correspondence players. Therefor I’m favouring either win/lose/annul or annul everyting.
Either way it could be possible to detect players, which are exploiting the rule to keep their rank by tracking the ratio of (timeout a losing game)/(total timeouts) and bring it to moderator attention if the ratio is unusual high.