Justa, my understanding of the "turning off the car" is that when the information is gathered by the software from the DAD system, it does more than read data but rather it somehow interacts or is detected and triggers a response from the vehicles OBD unit making it shut off or trigger a dummy light on.
Applus remotely diagnosed my pass-with-no-cert problems last year, and finally narrowed it down to a flaky USB port on my cheap PC. I moved my DAD cord to a different USB port, and my problems disappeared.
The OBD2 communication protocols involve data packets that are broadcast over the bus. All modules, including the OIS and/or scantool become part of the system when connected. Any module has access to every packet being broadcast, but they are programmed to only "pay attention" to packets that have been addressed to them. Similarly, any module has the potential ability to construct and broadcast its own packet onto the network. If two (or more) modules attempt to broadcast at the same time, the collision is detected by both, and they both back off for a small but random interval before re-trying.
This is the bi-directional aspect of the OBD2 system, and the OIS clearly needs to have the ability to do more than just "listen" to perform its intended job. This is where the potential for negative side-effects comes in, because a poorly constructed data packet can wreak havoc if it is addressed to an important module, inadvertently or otherwise.
Now, is it the DAD or the OIS software that is constructing the faulty data packets? The DAD is a relatively sophisticated FPGA device, so it potentially could be doing a significant part of the work. I don't know, because I would have to monitor and decode the data-stream between the PC and the DAD to know the nature of the workload, and I'm really not that motivated to go through the trouble and potential danger of pursuing that question.
Some-what related ... There was a video that I watched awhile back of two guys driving a vehicle with park assist. The passenger had hacked into the OBD system, and was able to demonstrate something kind of scary ... he winked, pressed a key on his laptop and caused the car to jerk the steering wheel out of the driver's hands.
I have similar thing happen on two cars . ONce the DAD was done with the downloading of info the car engine cut out by itself or maybe BAR turned it off who knows .The thing is , it has been known to happen . I just disconnect the device , turn the car on and back it out . I don't care who turnt it off just as long as it fires right up afterward .