In order to maintain thoroughly hsi philosophical standpoint of Anti-realism, he rejected two-valued semantics and took Intuitionist logic as the basis of his metaphysics.
It's particularly wary of science, or of the idea that science can tell us the truth about the external world, the view that's sometimes called scientific realism.
Whereas then when we perform the reduction, we are placing the whole realism versus idealism debate In abeyance, we're just gonna consider the pure appearances without regard to their ultimate metaphysical status.
Yes, I think initially what Continental philosophers saw in Sellars was that because there was a recent turn in Continental philosophy, the speculative turn towards a realist stance on the existence of the world.