Sherman may have been an anti-Semite, though I am unfamiliar of any instances. But it's certainly possible. Wasn't it Sherman who (ironically despite his middle name) said "the only good Indian is a dead Indian?" And he was certainly a racist who had no use for Blacks. After becoming the most hated man in the South (with the possible exception of Benjamin F. Butler) the truce he offered Joe Johnston was so lenient it would have allowed them to keep their slaves. Lincoln and Grant had to intervene.
No, that was Sheridan.
When I first read your post that Sherman and Johnston negotiated a truce, I couldn't believe it, thinking that it was Grant and Lee who did it at Appomattox Court House.
But I looked to try to check it out in an old book, The Story of the Confederacy originally written in 1926 by Robert Selph Henry, I was surprised to find that you were correct. Sherman and Johnson did meet and talk in North Carolina, near Durham's Station. That was a week after Appomattox, and after both had gotten word of Lee's surrender to Grant. By then, they had both known as well that Lincoln was assassinated.
Wonder why it took so long for Johnston to surrender and why Sherman took it upon himself to enter into a detailed agreement with Johnston without authority from Washington (DC, that is).
Incidentally, the mobile Confederate "government" - or what was left of it - approved of the terms of the Sherman-Johnston pact. No mention in the book, though, about its terms regarding slavery.