Why would you even need to search somebody? If you want to add them because you know them in real life, just ask them for their full username. Then go to your profile and in the URL replace your username with theirs and press enter.
If you met them on Armorgames, like on the forum, you can just click their username and it brings you to their profile.
If you met them on a multiplayer flash game, just ask for their username or tell them to comment on the game you are playing and you can click their username and go to their profile.
The only reason i can see you would need to search somebody is to add a random person you don't actually know as a friend.
They might put it in AG3 anyway though, because there are probably a lot of players (that for some reason) want it.