Terran didn't throw Asylon under the bus. Terran didn't even abandon Asylon. Terran went out of their way to ensure that Asylon took as little damage as possible. In fact, Terran is the reason that Asylon still owns Itau, as opposed to Kabrinskia.
First of all, according to the treaty, Terran had no obligation whatsoever to defend Asylon. Asylon had started an aggressive war against Kabrinskia. Terran's treaty with Asylon mandated help only in case Asylon was attacked, as it was a mutual defense pact. By starting their own aggressive war against Kabrinskia, Asylon released Terran from their obligations.
Second, even though they didn't need to, Terran laid put conditions in which they would come to Asylon's aid. This included putting all Asylon cities, and the southern 2/3rds of Asylon regions off-limits to the Astrum/Kabrinskia. If Astrum or Kabrinskia attacked Via or Itau, or started looting further south into Asylon's farmlands, the Terran would re-enter the war by launching an attack on Kabrinskia.
And that, boys and girls, is how Terran saved Asylon's ass, even though they were not under any treaty-bound obligation to do so.
