Their orders said they were to attack. So far as the Confederates could tell, the trigger was already pulled back on April 5, when Lincoln sent them out with orders to attack.
That they did not attack was completely the result of the command ship being given secret orders to not show up at Charleston. Nobody knew the command ship was not going to show up, because all the orders of which anyone knew said that they would lead the attack.
Very clever trick to start a war by convincing the enemy that you were going to attack them.
But it's simply ludicrous to argue that Lincoln "tricked" Jefferson Davis into starting war at Fort Sumter.
The fact is that Davis had long since ordered Fort Sumter to be taken, by one method or another, meaning by surrender or by military assault.
In Davis' mind there was no option for Sumter to remain in Union hands, period.
That's why there was no "trick", Davis simply did what he was most inclined to do: order a military assault on troops who refused to surrender.
And Davis knew it was a mistake because he was warned: