When you dilute ethanol with CO2 it reduces the removal of unwanted chlorophyll when comparing it to a pure ethanol extraction. Its all about context.
When speaking in terms of a adding a fourth variable of that can enhance control of selectivity to a CO2 system this statement is not incorrect. It’s all about the parameters. Of course if you are running supercritical at high temps and pressures with a large amount of cosolvent you are going to pull more chlorophylls. Its all in the parameters you run with. Read the whole article and not take one sentence out of context.