NVIDIA makes money no matter if the model is open weights or not. I don't think open is a concern for them and they'd very much like to be servicing China and their batch of open models I think. what's concerning them more likely is

A. The inevitable breakdown of their massive head start with CUDA and data center hardware. A serious competitor at real scale.

B. Anything that'll cool off the massive data center buildouts that are fueling them.

Seems clear that locking up a major potential competitor especially the minds behind it solves for A. And their ongoing machinations with circular funding of companies funding data centers is all about B - keeping the momentum before it fizzles.