Can't reproduce with the latest rcon locker plugin: http://www.sourcemod.net/vbcompiler.php?file_id=43224
(or silliums updated one for that matter)
Issue may only be present in the unmaintained
I quickly looked through the source of rcon_locker as i recommended it to a friend and he said it was unapproved.
It doesn't EVER regconsole/admin cmd for sm_csay, psay or say, it does however add a command listener which is only used to check if the player is connected or for newlines.
This plugin fixes some exploits still present in source games, for example on bad servers with idiots who have cheats on it still disables pointcommands which could be disastrous if left unchecked and can be quickly modified to include more generic commands to suit the owners preferences, eg disable kill command to prevent escaping point loss and it is a good knowledge-base for beginners to sourcemod. I believe it was unapproved incorrectly, did you even double check that issue? It seemed more likely that chatcolors plugin was the culprit..
Personally I'd say its worth keeping this approved purely for the client command logger it has inbuilt...
/e: Using latest sm 1.7
/e2: Tried in the games tf2 and csgo.