The way I read it, no synergy between EPA and estriol would imply it was EPA alone that caused Apo-B reduction, rather than a synergistic effect between EPA and estriol.
Suppose there was synergy, and suppose EPA + estriol Apo - B reduction WAS statistically sig compared to just estriol (we know it wasn't), then Amarin could argue it wasn't EPA per se, rather a synergistic effect that caused apo-p reduction.
I think we have enough with the factual errors (stat sig + patent official did consider Kura) to win the Apo-B point.