I'm not upset that WCS got a mention instead of Diaspora, Diaspora is quite short. WCS instead of TBP on the other hand.....
I guess it comes down to what perspective you look at things...
a) Diaspora is the newest and technologically most superior; yet the content for the player is limited to 5(?) missions and even the assets to build new missions are limited (which is part limit of the BSG-universe and part limit of the release)
b) TBP is the oldest and with Zathras trying to keep up; it also has large and diverse content for someone wanting to create missions; however the playble content is rather lacking compared to all that is in there originally: TBP only comes with a 5 mission EMW-arc and the 16 mission Raider Wars (which are both rather classic), everything else is optional and "sold seperately"
c) WCS comes out of the gate as somewhere in between both technologically and brings a mid range of assets to go out and work with. However it brings the largest amount of playbale content right out of the gate of any TC yet*
Also there is the magazines point of view which you have to take into account; not all readers of PC Gamer must be Fans of SciFi-TV-Shows but are Gamers, so it is reasonable save for a journalist/editor to assume that a Wing Commander-reference might be understood while a reference to B5 or to a lesser extend BSG might not be.
*I'm not entering WoD into the competition here because really stands on its own and has no other material out there that might make it interesting to mention from journalistic point of view