CT "Noooo" in Return of the Jedi

This is the same Force that allowed Luke to sense that his father, Anakin, the "good man", was still alive in Vader. Obi-Wan's point of view is not the "eyes of the Force". Obi-Wan and Yoda's other belief/point of view was that Vader could never turn back from the dark side...but the Force was under no obligation to shape reality according to that belief. The same goes with Anakin's Force ghost's appearance to Luke and the audience.

Anakin did not die 20 years before SW - literally OR metaphorically. Had he died spiritually/metaphorically speaking, the redemption would not have happened.