Primary testing is done using ASTM D4172... aka the Four Ball Wear Test, who's applicability to testing engine oil has been forever been called into question.
Looking at the overall conclusion:
Overall, it can be concluded that 6% of bioethanol fuel dilution can degrade properties performance (viscosity and alkalinity) and tribological behaviors of the synthetic oil. Ethanol fuel dilution may reduce friction, compared to pure gasoline due to its polarity and acidity. However, high acid in the oil causes high wear due to its corrosion on the surface, suggesting that ethanol-resistant engine oil should be produced in order to avoid serious wear from bioethanol.
I don't like the fist sentence. The sentence specifically identifies the "6% bioethanol fuel dilution" as degrading the performance properties. Going back through the results though, the E0-SO simple ALSO degrading the performance properties. In most cases, E10-SO had nearly identical performance as E0-SO. Yes, it was worse than the virgin synthetic oil, but they were both worse. The conclusion only discusses the ethanol blends as affecting performance, when the reality is that any fuel dilution affects performance.
The rest of the conclusion seems pretty straight though. The more ethanol in the dilution, the worse the performance properties.
Of course, all this is dependent on whether you believe the four ball wear test is even applicable to the engine environment.