Maybe I should clarify. As I understand it, the kind of vulnerability being discussed is something like a Chinese model invisibly "realizing" that it's working on an American project, and then deliberately leaving subtle security bugs in its generated code for Chinese hackers to later exploit. As far as I know, that scenario is hypothetically possible, but has never been demonstrated to happen in the wild. Admittedly, I could be wrong about that! If anyone has evidence to the contrary, I'd love to see it.

Of course, one could retort that gathering that evidence may be nearly impossible now, but my point stands: in the future it might/probably will be possible to properly audit open-weight models. Closed models, on the other hand, will always be a black box.