Greenspun had other companies before Ars Digita. He took ICAD/Concentra public and also co-founded ConSolve and Isosonics.
It may be true that no programmer with any sense would work for him - I don't know him personally. But given how cheaply you can start a company nowadays, he certainly doesn't need investors. And as I understand it, he's not entirely retired: doesn't he teach a course at MIT?
I don't know - "may be true" is just conceding the point to the grandparent, because I have no personal knowledge of Greenspun, and from his username, it appears that the grandparent worked at Ars Digita. I've heard that Greenspun's management-style was pretty abrasive and he could very egotistical, but this is all hearsay.
It may be true that no programmer with any sense would work for him - I don't know him personally. But given how cheaply you can start a company nowadays, he certainly doesn't need investors. And as I understand it, he's not entirely retired: doesn't he teach a course at MIT?