Off the top of my head. In his return campaign for Congress the newsletters came up and Paul defended them as a whole but nobody had specifics at the time (since they were stored in that one archive, no internet, etc.) so it didn't go beyond that.
They didn't come back up until 2008 when Reason and some others started putting the actual content online, etc. and that's when he tried the "I didn't read them" line to his defense.
I don't think anyone has ever really thought Paul wrote them. It's hard to reconcile the offensive newsletter content with anything else regarding Paul. We have to assume Paul spends 99% of his time not making those arguments, then he gets alone and writes a newsletter with his name on it that does. Or we can take Rockwell and friends who never have had an issue worrying about the barbarian hordes and how if you just break the right skulls we can get around to liberty. He thought he was out of politics after the Presidential run, Rockwell/Rothbard came to him to use his name on newsletters to keep the movement going and he was fine with that. I assume he only ever slightly checked in on the whole affair but let them just take care of it and cashed the checks. I don't know why people go for the more difficult "racist" attack angle when the whole derelict management aspect is there and even backed up by Paul himself. And one would think, quite relevant to someone wanting to run the executive branch.
Actually, maybe the most logical theory for Paul's "defense" I've heard is that it was Carol Paul who wrote them.
For the record, the Paultard explanations are:
-Ron Paul is the most ethical man in history and it would be not just unethical but a crime to out people who don't want to be outed. Their privacy in writing the newsletters must be preserved.
-If you read the newsletters there are three or four offensive sentences, but this is just the wording. Everything else is actual the truth, but the PC police are trying to crucify the savior for telling the truth instead of spreading more lies.
-Everyone already knows about the newsletters and heard about it back in 1995, it didn't matter then, Ron Paul won the election. It doesn't matter now, people are tired of hearing about it.
-Jeremiah Wright. Jeremiah Wright. Jeremiah Wright. Bill Ayers. Jeremiah Wright.
-Israel/the Kochs/Cato has ordered these smears of Ron Paul because they're jealous of his success!
-We have the First Amendment, no one should be punished for anything they say.