So, they're locking out things that can brick the card (flash ROM/fuses, screw up thermal sensors) and apparently a hint of OS security (the Falcons that respond to userspace commands can no longer access physical memory, only virtual memory). The latter sounds somewhat bizarre, considering the firmware should be fully under the control of the driver, not userspace (I guess/hope?), but not unreasonable. Maybe there are software security reasons for this.
Nouveau is free to continue using its own free blobs or to switch to nvidia's. If they start adding restrictions that actively cripple useful features or are DRM nonsense, then I would start complaining, but so far it sounds like an attempt at protecting the hardware while maintaining manufacturing flexibility for nvidia. This isn't much different from devices which are fused at the factory with thermal parameters and with some units disabled; the only difference is that here firmware is involved.
NV seem to be turning friendlier towards nouveau, so I'd give them the benefit of the doubt. If they wanted to be evil, they would've just required signed firmware for the card to function at all. The fact that they're bothering to have non-secure modes and are only locking out very specific features suggests they're actively trying to play nicely with open source software.