It generally was always the case. Nvidia was a huge stakeholder in technologies like OpenGL, OpenCL and Vulkan, supporting Khronos' goal to further expand the FOSS API ecosystem.

Linus is probably referring to Nvidia's "open" driver series and capitulation on EGLStream. Nvidia got a terrible reputation for refusing to implement GBM for Wayland desktops, insisting on the nonstandard EGLStream protocol for close to a decade. Around 2024 (550-series drivers) they gave up and reworked their drivers for GBM-agnostic usage, fixing Wayland and generally resolving the biggest gripe people had against Nvidia hardware.