If it did not happened with every 6C/12T maybe the problem could be related to AMD processor ? I do not have any knowledge for now, so I cannot really tell.
I tried to redownload the game so I can get a fresh config, and when I launched it, SteamVR didn't messed up, the game got the slowdown as you seen earlier in the vid, but I could get to the menu and launch a game. Here's the log though : https://pastebin.com/0mZKp4TH
Some minutes later, I launched the game again, and SteamVR crashed like I said on my first post. The log is here : https://pastebin.com/JTtUwLQ6
And you can get the log when the game is launched with threadLimit at 8 : https://pastebin.com/wL4RYc7Q
Good luck on this one, I'm still here if you need more information or need someone to test any fixes you can find.