As far as I know, UT3 (for the PC), in spite of all its faults, does not count bots as players in the server browser. However, that was a shortcoming of UT 2004.
It used to count them before the first or second patch and definitely before the web admin tool came out. I stopped playing that game a long time ago for a bunch of reasons (mainly hearing 'take it!' every 5 seconds among other serious flaws and one of the developers, Jeff Morris, being an asshole to me and other former-fans on multiple sites). I even used to mod for Unreal games. Last time I played UT3, there were so few players that GameSpy was tracking stats for bots and there was absolutely no working cheat protection/prevention. Even Crysis managed to get the online part going better than UT3. Sins may be bad with people sitting in the lobby online playing games, but it pales in comparison to all the issues you deal with in those other two games on top of low player counts.
sold 100.000 copies (or more) - 50 players are online. You could say 50 is not the vast majority, all right, but you have to ask: Why 50 players only ?!?
Have you ever considered that people also like to play the singleplayer or play with friends? I haven't signed onto ICO in a long long time because I don't like games online with random internet people. No offense to you personally, but my experience with them has always been abysmal, but with friends and AI opponents I get a more consistent experience. Also, it's possible people may be out playing GTA IV. Sins is not the only great game in town anymore.
Maybe it would help if Ironclad held another online night with the developers/publishers?