The real Satoshi would likely be in a situation where claiming complete ignorance would be a poor strategic choice. If the real Satoshi were to make that claim, he (I'm assuming it's safe to use male pronouns) would be making a gamble that nothing would come to light that would contradict that claim. It's possible that Satoshi would feel comfortable making that gamble, but there is a significant probability that the real Satoshi cannot credibly claim complete ignorance. The fact that Dorian made that claim is weak evidence that this is a safe gamble for him to make, and it being a safe gamble is weak evidence that he is not Satoshi.