it seems a bit ambiguous in the movie. Did he actually know it and was prepared to die to protect the computer code? Or did he truly not know it?

My personal belief was that he did know the code and was just bluffing, not thinking they would actually shoot him over it.

Just wondering if the script or some other inside knowledge sheds any light on this.

if he did actually know the code, it might have worked to bring Holly and some other employees up there and shoot them in front of Takagi as added incentive for him to disclose.