I literally think some of this comes down to the fact that not everyone can (or even would) launch a pre-emptive strike. The IR *knew* that eventually another attack from the Israel/US coalition would be coming, but it is to their benefit that the whole world sees that they didn't start the violence.
But if you're a Trump minion, the only reason not to start a war is that you are weak. So they figure if Iran isn't starting wars, then clearly it's weak & will collapse the moment it is attacked.