There's really no evidence that Hamilton's observations on the 16th were wrong. The recce on the 17th certainly didn't prove him wrong. He didn't claim in his dispatch on the 16th that the confederate positions were entirely abandoned. He claimed they were drastically weakened.
You can attack Hamilton all you want, but he was a West Pointer and a combat veteran, and he was there. His view has high credibility as a primary source.
The important point is that he did indeed propose attacking, just as he later wrote.
Huh, Hamilton claimed the enemy was gone and there were no guns in the embrassures. Someone was sent to have a look, and was killed no a gun in one of those "empty"embrassures. I think it's pretty clear Hamilton was wrong.
One should look at other accounts. The works were not weakened.
Heintzelman's journal reports he "directed General Hamilton to throw up a smalll work and this morning with this artillery prevented the Rebels from strengthening their works opposite. It developed ten Rebel guns but Captain Thompson silenced them."
Hamilton himself sent three messages, which are obviously out of order in the OR, initially (before 1500) stating their fire had developed the enemy guns,* and forced their working parties to stop. Then at 1830 he sent a message that they'd knocked out a rebel gun at 1500, and the enemy had ceased fire. Finally on the night of the 16th/17th (arriving mid-morning on the 17th at Heintzelman's) is the one you like to quote, stating all the infantry had abandoned their works and, in conjuction with his coversation on the morning of the 17th with Heintzelman, indicated the artillery was removed. He stated he would attack and hold the works with a single brigade.
* In case you don't know the meaning of "developed," it means caused them to open fire, revealing their positions. It is a standard tactic, and also a standard tactic to stop firing and, if possible, move firing points if this happens.
The rebel left, under DH Hill consisted of 8 brigades in essentially three divisions:
Rains' division at Yorktown, with Colquitt's and Featherston's brigades
Early's division in the redoubts, with Early's, Rodes' and Ward's brigades
Wilcox's division at Wynn's Mill, with Wilcox's, Colston's and Winston's brigades
Four regiments of GT Anderson's brigade had been stationed behind and between Wynn's Mill and Dam No. 1 the day before, but were sent to Dam No. 1. Heintzelman saw these four regiments moved over to the left.
Normally, only two regiments of Wilcox's division actually manned the front (including Wynn's Mill and the Upper Dam), doing 24 hour shifts. The other 8 full regiments were kept out of sight in the rear. Even if you suppress the regiment at the dam, 2 brigades are close enough to move up during the 20 minutes for Federal infantry to cross the intervening ground.
However, there are no mentions of the works being abandoned in any rebel source. It's a completely unsubstanciated claim made by Hamilton. That it was false is shown by Lt Wagner's death.