And Slutskaya not landing 3-3 in practice is a negligible point if nobody attempted the 3-3 in the SP or FS. It's what you bring to the competition that matters. If you're saying Shizuka had such a cushion on Slutskaya, then why didn't she attempt the 3-3?
Maybe in 2006 - at the time of the Olympics - Shizuka was unbeatable because Cohen and Slutskaya weren't at their peak. But as far as whether Slutskaya or Cohen would beat Arakawa if all three skated their best, but BOTH of their personal bests (Slutskaya 198.06 and Cohen 197.60) are considerably better than Arakawa's personal best at the Olympics in 2006 (191.34).