I don’t know colonialism could be defended; they’d probably simply be better off if they’d never been colonized to begin with. Anti-colonialism left them with modern weapons to correct ill-drawn boundaries, and too often they used those weapons instead of diplomacy.
Every time African countries have used the anti-colonialism excuse to blame whitey for all their problems, it has led to mass slaughters. When they kicked white farmers out of Zimbabwe, it just led to starvation and ethnic cleansings. Which continent has the worse genocides, and who is doing it? It’s not whites. The Nazis blamed the wrong people for their problems, and so are black people who say white people caused all of theirs.