He was wrong in that he was wrong. I don't blame him for not being to predict what happened, but the industrial revolution had already begun. He had to have been aware that technology can increase efficiencies, and he didn't account for that properly in his models.
He was wrong in the sense that Newton was wrong about physics - he accurately captured an important dynamic that held absent extreme violations of stasis - e.g. Newton was wrong about relativity and quantum mechanics. Nothing Malthus did was absolutely wrong - it's just that other forces that were unleashed overcame the dynamics he accurately observed.