It is not very clear from the writing but he analysed the QuakeWorld source. QuakeWorld is the internet optimised version. So this is for server and client having latency between them.
To someone who does not know what QuakeWorld is, that line does not explicitely say that it is about the online multiplayer engine instead of the "Quake engine" that was powering the singleplayer game.
> QW is "Quake World" project, where Server and Client are meant to run on different machine (notice the client staring point is WinMain (in sys_win.c), whereas the Server stating point is main (also in sys_win.c)).
In the middle of the index, in the "Opening the zip and compiling" section. Ok, it is explicit, but it is not too visible there... If someone jumped right into another section, how would they know.
After being called out twice, at this point I would have thought you would given up. Stop skimming and start reading if you are going to comment on articles.