When did you last check?
I can't tell if you are being sarcastic, or if NVIDIA support for BSD has come along a lot since I last checked.
Nvidia have been a lot more on the ball for things that aren't Windows for a while since they started going all in on Tegra. Yes, it's not the best support for gamers but make no mistake, this move to a *nix system would have been under the advice of Nvidia.
Anyone saying this makes Switch more vulnerable is hopelessly wrong. The Wii and WiiU were a mess and far less secure than this will be.