Illustrator license

If you want to keep running antique software that Apple has blocked, you need an old computer. You may find a used one fairly inexpnsively. 

I'm not sure what "false advertisment" you claim. Adobe never advertised "we will keep giving you new free updates forever when Apple make incompatible systems". Supporting new systems is a new feature. You get new features when you pay for an upgrade. Seems fair enough, why should Adobe do all that work for free? Indeed, wouldn't that amount to Adobe subsidising Apple?  

By the way, just some extra background

- the software would be Adobe Flash Professional -or- Adobe Illustrator. CS6 included both, but they are entirely separate

- Flash Professional is now renamed Adobe Animate.

- Flash Professional was mainly used to make animations for use with Adobe Flash Player. Adobe Flash Player was closed down by Apple, Microsoft, Google and Adobe at the start of this year, and can no longer be obtained or used.

Technology changes all of the time. Like the computer your son used that probably saw better days and had to be replaced, Flash needed to be replaced with a newer software called Animate. It isn't that your license is invalid, you can still use any computer with that same operating system that you had. Flash however was retired and older versions are not compatible with the newer operating systems. This isn't fraud,  just how technology works. 

The software has certain requirements that your hardware has to meet and if it doesn't meet those requirements then you can't run the software. Even back then with perpetual licenses you had to buy a new version when you updated your equipment. So that is what's happening.

Software companies have to invest quite an amount of money to keep their software up to date, so they need to charge for that. Get an old, used Mac and then you can run your CS6.