They make their AI accessible to anyone. Sounds pretty open to me. Maybe not for developers, since they associate „open“ with open source, but surely for everyone else.
Defining it as such, makes it meaningless. Open, in software, means much greater access.
It might not be the openness that OSS developers expect, but they're providing a platform for anyone to build on top of, whether it be hobbyist projects or commercial products.
Also, don't forget, it's only due to the Magnusson act and other acts that we have rights beyond what Ford wants to grant us on our cars. (Since Ford was the one in that lawsuit, Toyota came later.) If it were up to manufacturers, the hood would be welded shut, we wouldn't be allowed to use aftermarket parts at all, and they'd take a cut of every Uber ride.
I don't see Congress acting in the case of OpenToTheGeneralPublicAI and ChatGPT, unfortunately, but the car analogy falls short because software isn't the same as physical goods. Toyota's info about what cars are doing after being sold is limited, but they have to get them in the hands of customers. OpenAI can just let customers use ChatGPT via the website or an API and it's usable by customers.