It all depends on "who" and "what" we want to believe. Douglas Southall Freeman is my favorite writer and if he says Johnston gave his report to Lee early on the morning on July 2 - and said the Round Tops were unoccupied, then I blame Longstreet for not moving fast enough that day and a super slow attitude towards obeying Lee the whole time they were at Gettysburg. Of course, Freeman does. Who else? The famous Park Ranger at Gettysburg, Matt Atkinson, certainly feels that way too. If you google him, you will be able to see and enjoy quite a few lectures and battleground walks that he has led at Gettysburg. They're fascinating to watch and listen to! As for Lee, and it is fun debating all of this with you and everyone else, we know Lee had 100% confidence in his troops. He said; as long as they were properly led, his men could accomplish anything. But the leadership with his corps commanders was more than lacking those 3 days; especially with Longstreet. Did "Old Pete" forget he was NOT Lee's boss? Did he think that just because Jackson (a commander more like Lee when it came to offense) was dead, that he would be the man Lee would trust the most? Sadly, they were like oil and water thru out the entire Civil War. Back to Samuel Johnston, he made his journey early in the AM, he gave Lee his report and Longstreet - who had to have known what Lee expected, should have had his corp ready for action that morning. But he didn't.
So we are reduced to blaming Longstreet for not being a mindreader of a decision that had not yet been made (thus Johnston's mission in the first place).
Bobby Lee lost control of matters on July 2. Freeman's extended apologia doesn't counter that. Great commanders plan, then adjust and improvise. They don't hold on to a plan devised with information that's seven hours old by the time troops are getting into position (recall how long it took the sainted Jackson to do the same thing at Chancellorsville) based on information that relied upon circumstances not changing.
Lee is reported to have spoken highly of Meade, but his actions on July 2 suggest he held Meade and the Army of the Potomac in contempt.