Tegmark and Musk are both dumb people posing as intellectuals, but they are always in it for the attention, that's why their opinions are so out there. Tegmark totally didn't make up the one-in-six chance because it sounds scary.
You can't de-escalate a bully, let alone a madman by appeasing him. It's just not how it works, but these two geniuses always know everything better. WW3 alert my ass, that's what Putin wants you to be, scared. But we are not scared, even if the worst happens we are ready for it. It's Putin who should be scared, he is surrounded by enemies, just about everyone around him is waiting for him to be put down, they might even end up doing it themselves if he keeps this up. So far the Russians proved to be adequately level-headed and responsible when it comes to avoiding nuclear war, which probably only be nuclear on their side, because we have better tools in our arsenal that can be used to take them out.