Many people can turn a scientist's findings into a practical exploit. Therefore there was no reason to include the original cryptographer in the trojan development process. Let's consider the potential that this was not NSA-bound. It opens the amusing possibility of cryptographers selling their findings to the highest bidders, just like security
https://www.youngandthrifty.ca/how-to-buy-stocks-in-canada/ may. If a world-class cryptographer is not working for the NSA, they will probably be watched. Are academics above such shady transactions, or is the prospect of a few hundred thousand dollars sufficient to allow for such synergies?