This is regarding the other games, other than ZP!S.
I simple doubt Left 4 Dead 2 Server has any players at all since most if not every player choose modded servers.
In the following website, http://soldiersofdemise.com/ you can still see other games with the servers being stated as "CLOSED". My suggestion is, if those games wont have SOD servers anymore, they shouldn't be seen in website, they should be removed. If Rust, CSGO, etc, wont have servers, they should be removed. I think this is web designer work.
Servers with no players at all should be closed to save up money costs.