It would surely be nice to have such a command, as I have had this situation a few times now... where ppl had to leave for whatever reason.
But I see a problem in the line "Anybody could use the savematch command", as this will most likely be overwritten every time you save such a match, thus erasing old states and making it possible for unauthorized players to overwrite an existing savegame.
Another question came to my mind: as the Graffiti Matchservers are mostly used for matching, we might have the same problem there even if only opped players can save games... any idea for a workaround? And... what data do u want to save? like, it can only be saved serversided, so... no way to save player scores, dont you think? As it will probably be hard to have exactly the same players (with the same IP, ID, whatever) on the server again.