It's an interesting observation in a number of ways. Forrest may have been right. Lee's army was worn down and there were large numbers of desertions because of Sherman's operations in Georgia and South Carolina. Mostly what he had with him were die hard Virginians - who were defending Virginia. They were quite literally defending hearth and home. Lee didn't have too many options as to what direction he took when he finally got out of Petersburg - he was pretty well surrounded by then with huge numbers - but if he'd gotten food at Amelia Court House perhaps he could have joined up with Johnston in North Carolina. But it might have been an even smaller army! If Forrest had told his Tennesseans and Mississippians we're finished here, boys, let's go help Lee over there in Virginia - he might have had a real small group following him out. They would have been more concerned about their own homes and families. The stage the war was at when Forrest made these remarks to Maj Powhatan Ellis, one of S D Lee's staff, was a terminal one - and that was why he turned down the suggestion of taking his troops to the Trans-Mississippi or even to Mexico. The Confederacy was done - home was what the average soldier was concerned about by then. When Hood's army mostly dissolved after Nashville, Johnston received only a fraction of his troops.