But yeah, the fact Putin opted for the mobilization route probably means he won't/can't go the nuclear route.
They could explore this possibility further once mobilization fails to have the desired impact and when they lose a lot more territory, but at that point it won't win the war, it can only accelerate their own defeat since NATO will swiftly respond with conventional weapons only.
At least that's the general consensus among all the generals (whoops), and that former oligarch bloke that wrote a book about Putin.
There is no winner in a nuclear winter Derek!