Interesting! I don't remember ever hearing about that at the time. I'm not saying that I don't believe you, but I'd be very interested if you had any links or references for that.
For the three years (2002-2005) I worked on a DARPA Grand Challenge vehicle, my main desktop machine ran QNX. I could build and run the real time software on it, connected to either a simulator or cabled to the actual vehicle up on jacks.
No, this was because Quantum Software thought that they were going to compete with Windows on its own turf somewhere around 1991.