The statement is undoubtedly correct that the hold which the infantile experiences have on the libido—with the pathogenic influences this involves—is greatly augmented by the regression;
If Freud had just said that sexual relationships are particularly sensitive to or tend to reflect or bring out one's inner child, I think I could get behind that, on a materio-atheist point of view. I think(?) most psychologists today would say emotionally deep or vulnerable relationships instead, which I would agree, but that raises some thorny philosophical and evolutionary questions. I guess I can respect the thoroughly anti-religious viewpoint here, even if I don't agree with it. My guess is that I would resonate with William James's approach a lot more. Add it to the list...
