Your 36 (!) year old son can’t find any other options by himself?

Part 141 - FAA approved specific syllabus for both ground and flight instruction.

This means they cannot deviate from their approved syllabus and can certainly NOT authorize a different groundschool then the owner they’re approved to use.
So if it’s not this 141 school but another you’ll have to abide by their syllabus they are required to use.
If you’re set on doing your own thing you need to find a Part 61 school but even then they can insist you follow a particular track in order to get a sign off for written or practical tests.