What do you mean by LAN support? It is easy to have private games with password protection that only your friends can see. The entire multiplayer FAF experience is built around using the FAF servers which aren't accessible over LAN.
LAN would be something that is supported by the game code itself which the networking we do not have great access to and is a pain to work with.
All that being said it still should be trivial for FAF players to host private local games with their friends as is.