This is incorrect. Nuance was a company that originated decades ago, SRI did build Siri, using Nuance's speech technology, but Nuance itself did not spin out of SRI.
That's true, but technically, the company that is named "Nuance" today was originally named "ScanSoft". They bought the original Nuance and assumed its name.
It's a bit like Symantec, which bought everything, including its name.