Locked engine

No, that is not true. If it locked up from lack of oil, the motor is history now.

What that "someone" was refering to is a low oil sensor that shuts the ignition down. The only way to check if it's a possibility is to try and turn the crankshaft mannually. I would remove all the spark plugs and try and rotate the crankshaft. If the engine turns by hand it isn't seized up from lack of oil. It is a slim chance given your description but worth a try. If it does not turn by hand with the spark plugs removed it is seized and, as Wrenchtech said, history. Hope this helps.

There is nothing in a GM vehicle that shuts the engine down due to low oil pressure.

There would be nothing to invent. It would be just a matter of wiring and software updates but they have chosen not to do that as it would be very dangerous for a car to shut down unexpectedly.

I guess I wasn't real clear. I did not mean to imply there was such a low oil shut down on the vehicle. I only meant to say that the ony way to be sure the engine was (or was not) seized is to use the method I described. For the record there are some small engines for lawn tractors and the like that do have a low oil shut off that is a simple ground circuit that is interupted if the oil reservoir drops to an unsafe level. This is where some people get the idea all engines have it. Sorry if I was misunderstood.

As far as implimentation, it would not be hard (as Wrenchtech indicated) for them to wire in a warning that gave a short amount of time to bring the vehicle to a safe stop when a severley low oil condition indicated. Most engines would be able to withstand even a brief low oil pressure condition over a no oil pressure condition. Repair/replacement revenues are the most likely reason the effort has not been made to develope this further.

I'm afraid there is no safe way to shut a car engine down while someone is driving it and that is why you will never see that on a motor vehicle. This isn't your lawn mower in the back yard and people's lives are at stake. The manufacturer can install warning systems which they already do but that is the extend of control that they can safely take. The rest is up to the driver.