My guess is that it has something to do with those orbs we're being sent to find.

[ And for all he knows, maybe it is some working through the Force, but he's never known any practice that involved undoing an action made. The repercussions seem too great if changes can be made like that.

But Obi-Wan firmly believes that undoing his regret would save countless others that never deserved the sort of fate they were dealt. This, as it so happens, includes young Cal. ]

But anything that has the power to undo a regret is one we shouldn't underestimate.