I'd agree with your observations, except: is it wise to control for socio-economic conditions? "Well, [he/she] is gorgeous, brilliant and kind, but that's probably all because of being born within a family with positive attitudes toward physical and mental fitness, being given the free time and economic wherewithal to self-improve, and being placed in peer groups that would encourage such improvement, so I guess it doesn't really count."

Life doesn't work like a D&D stat Point Buy system - although you're right that it's sometimes similarly possible to trade INT for CHA or vice versa, that doesn't make them inversely correlated. Some people are lucky enough to have more of both to begin with, and many people are lucky enough to grow up with influences that increase both.

On the other hand, even physical beauty is partially subjective. Maybe Eliezer's perceptions of it are subject to some sort of halo effect? The "known well enough to observe them in any detail" caveat seems to suggest a factor in that direction. Aside from effects of fashion, lighting, etc., real physical beauty is a superficial thing that you can judge with a glance, not something that only becomes apparent after the more important characteristics have shown themselves.