I have my doubts of Sherman, because he was under the direction of both Grant and Lincoln. Johnson was well aware of the terms and conditions of Lee's surrender, and applied to Sherman on those terms. As for Lincoln's "Letting them up easy", he had proposed his reunification conditions as early as 1863. The Confederates thought it was a ploy without any real substanct, to simply get them to put down their arms. Once disarmed what could they have done?
It was President Andrew Johnson trying to carry out Lincoln's plan that got him into the trouble that lead to his impeachment trail. Lincoln may have been able to circumvent some of that had he lived by the strenght of his popularity with the northern people. That popularity may have been what got him killed by Booth, because no one has ever proven beyond a reasonable doubt who gave Booth's his orders in that conspiracy.
As it was, reconstruction proved that those old southerners were well versed in northern treachery. It was Grant himself that interceeded on Lee's behalf.he terms of that surrender.