Because they run linux, thats what all of their servers run, thats what they wanted running on them, and thats what they put on them long before i came along. They don't want windows servers in their network for what ever reason their net-admins have, i've requested a windows box previously but it just won't happen (i guess they don't see the need/don't want to spend money on licensing windows for game servers)
I'm not sure why you keep questioning all this, thats the way they box's are setup and i'm working with what i've got, if this server won't work, or turns out to lag or not run right, then we won't host it (in its current form).