Ok so most of the possible theories have been stated. I believe personally that since in no world real or fantasy is peace forever lasting that Squall who is the overall commander of SeeD and it's Garden bases would see the neccessity of continuing operations. All of the cadets who stayed for the Gabaldia garden battle would be experienced SeeD candidates (if he didn't raise them merely for being able to hold off so many soldiers) Esthar is a mess due to the Lunar Cry and if you listened to the game script one of the characters mentions on board the Ragnorak (soon after returning from space) that a representative of the Estharian Government (Kiros) has contacted you in regards to negotiating SeeD help in eradicating and controlling the monsters falling from the sky. Gabaldia is screwed. Their government is in an anarchiac state with no clear head of government. Dollet will possibly be afraid of further attacks as will FH and no doubt Timber would launch a full liberation front. Aside from all of this Selphie would like to repair Trabia Garden and no doubt unless Squall ordered Gabaldia Garden destroyed they would need that repairing too.
i agree