Yale didn't offer the JD until 1971.
Yup. Some schools offered to let older grads. refer to it as a J.D., if memory serves, because of complaints. He earned the two-year Bachelor of Laws degree common in most common-law countries but may have been granted permission from Yale to call it a JD.
When the lawyers chose to upgrade their credentials via the "professionalization" process that had turned bachelors degrees in medicine etc. into doctorates like the MD--you can still find just a few people who earned a BVM and became veterinarians or a BPM and became podiatrists, but not many--they chose to make it a 3-year J.D. that was intended to be the "scientific study of the law". You can see its legacy in the fact that for physicians, dentists, and lawyers, the next degree in sequence is a master's degree. You don't often see the medical versions but many JDs will get a LLM--Master of Laws, in thinks like tax law esp. After the JD and a LLM they can apply for a SJD (Doctor of Juridical Science) program, which is a research doctorate like the PhD. If you look at the Wikipedia article on the JD you'll see that it is explicitly not considered the equivalent of a research doctorate. It's in line with other 2-3 year masters degrees like the MPH, MFA, and until recently the MPT.
Anyway, this guy earned a bachelor's degree--probably two of them, actually--but not a doctorate, and certainly not a research doctorate. He has the qualifications necessary for writing on the law but wouldn't have had even the minimal research education that comes with a JD.