You need 22 quarters plus they average it over your working years. He would have had years and years of 0 contribution during his public employment.
I know that some public employees are now being put into social security rather a publicly funded pension. That happened with NASA and other government agencies a long time ago.
Yes, that is how I understand it too. But if he worked in the private sector before taking a job with the city of Detroit and worked 22 quarters, he could be drawing a SS check correct?