Mandela was never anti-Israel, even though he is one of the few world leaders who would be absolutely justified to be.
Instead of bashing Mandela we should have asked mechila from him, as the Israeli government had made an alliance with the rashaim who had supported the Nazis during WW2 and created the Apartheid system in the image of Nazi Germany. To go further and to call him a Sonei Yisrael is a chilul HaShem. The real Sonei Yisrael were the people he spent his life fighting!