There is currently no legal precedent for joke theft. Many people create the same current event jokes. So, this comes down to Intellectual property theft. Law

There is currently no legal precedent for joke theft. Many people create the same current event jokes. So, this comes down to Intellectual property theft. Lawyers at Conan's level are retained. I think that they do not want to be the top search result (as they are today) for joke theft and this was a mitigation attempt.