Code has more value than if it can be ran or not. Its 4 decades of problems and their solutions. For anyone who wants to do any work in the music notation space, it could be quite invaluable to go through the lessons learned, to see things from another perspective, especially one that went all the way to production and a long period of commercial viability.
That is theoretically possible, just seems very very unlikely. Finale is “millions” of lines of code, old legacy code that spanned dozens of OSes. Have you ever tried to read huge legacy codebases? They are hard to read, and I’m dramatically understating it. The time it would take to read and extract lessons learned from it could exceed the time available to do any work in the music notation space. Most of the lessons that are there to extract are lessons that no longer apply to anything. Not being able to build & run the code would reduce the ability to understand it by another multiple factor. It would be far more efficient to hunt down and interview the Finale devs, or spend time working on another product and learn from it.
All that is beside the point that Finale devs are under zero obligation to release their code, and generally speaking they have a decent list of reasons not to, plus some specific ones I speculate.