What was Grant basing this statement on? The fact that Lee, never a political animal, did not go on a public speaking tour to denounce the former CSA? He returned to his home, found employment as the president of a small college, applied for a pardon, lived up to the requirements of his parole, and urged that all other ex Confederates do the same. He turned down multiple hugely lucrative business opportunities to use his name because he did not feel he could accept payment w/o services rendered.
" He had been superintendent of West Point earlier in his military career, and more importantly, he had a very recognizable name in 1865. The college, mired in financial difficulties, needed a prominent person to help raise funds. At first Lee hesitated, but on the advice of friends and family he eventually accepted the position. He wrote to the trustees that he believed, "it is the duty of every citizen, in the present condition of the Country, to do all in his power to aid in the restoration of peace and harmony...... Lee's personal involvement with many of his students reflected his desire to create a new generation of Americans. In response to the bitterness of a Confederate widow, Lee wrote, "Dismiss from your mind all sectional feeling, and bring [your children] up to be Americans."
One wonders what else Grant expected from a man who had lost practically everything including his health during a war he did not wish to participate in.