Saab wouldnt shut down the deal, but may change the ToT part of it.
Yes the Grippen has a lot of US parts, yes Saab and Boeing are together in the TX program, but that has nothing to do with this case and wont matter if Saab thinks its tech secrets may end up on Boeings table.
Boeing works on and with many different military customers all around the world. It is standard for these projects to involve access to secret and nationally sensitive data and technology.
It seems naive that Saab thinks that Boeing will steal their technology when that should be held within the military side of Embraer. If this really is a risk, then the way to overcome it is for Embraer to enact controls to ensure data resides where it is supposed to and accessed only by those who are supposed to. This really is standard industry practise.
Boeing and Lockheed often develop stuff together... do u think one of them would just give up its tech to the other? dont think so...
For military contracts in most cases those companies work together for the US Government who owns the technology and is funding the work, not the respective companies. Either way, the companies control access to their information, ensuring that this doesn’t become an issue.