I just use Barlow because, like Sickles, he was not well-liked in 1863 and he threw his men under the bus after the battle. I'm not saying his move was on the same level as Sickles. Not at all.
I agree with every tactical argument against Sickles. I concede he disobeyed orders, even though Meade could have done more to make sure his orders were followed. Meade could have relieved Sickles of command like a coach benching a player mid-game. Meade, like Lee, had an "if practicable" moment of which Sickles took advantage. Meade, of course, does not bear the blame for this disaster. That rests with Sickles.
I don't believe that the actions of Sickles on July 2 have shaped the memory of what happened on that day. I would argue that his actions after the battle (and after the war) have shaped the memory of what he did on July 2. I would argue that his ceaseless attacks on Meade, his testimony before the Joint Committee, the Historicus essay, the scandal over the money for the New York monuments have all shaped our memory of Sickles on July 2. Also, let's not forget that Sickles was toxic for a couple years before the war due to his killing of Philip Barton Key.
If Sickles had just gone away after the battle, would he still be the target that he is today? Or if he had returned to service and redeemed himself like Barlow had done in 1864? I could see this much argument over his move on July 2 if it had cost the Union the battle.