The response message does appear only for the client that the mod is downloaded on, but the command the player types is also sent to the server chat.
player with the mod (executing the command with the output "This is a mod")
a different player w/out the mod in the same server
As you can see the other player can see the commands that are executed. Is there a way I can prevent the command from reaching the server so that it doesn't display in chat?