I read this in the tournament rules:

"If a player meets his deck’s victory condition before the time limit has been reached, that player earns a match win and his opponent receives a match loss."

I can't find any reference to a deck's victory condition - is there a winning condition for each warlord?

Victory condition and winning the game are the same thing.

"If a player meets his deck's victory condition..." simply means collecting planets, killing warlords, or discarding opponent's decks.

It also future-proofs them against releasing alternate victory conditions in unique warlords, or something like Trench Run in Star Wars.