True nature
Demonstrating supremacy was an efficient and easy way to achieve certain goals, and the three Overlords seemed to be aware of this fact.
As such, they had revealed their strength before vanishing, leaving behind millions of beings that had been scared witless, unable to grasp how fortunate they had been to survive the 'simple' warning.
Jason couldn't believe what had happened either.
What happened a few moments earlier was the most unlikely and dissatisfying way in which war could end.
Not only was it a tie, but the reason the Great Argos war had been halted was still not solved either!
Despite being weakened, Jason assumed that some of the sent troops of the foreign races were still present, and he assumed that the forcefully ended war would bring forth more problems than the three Overlords had tried to end.