Yes, they didn't reveal the Firefox bug or the details of NIT. And yes, Tor browser could still be vulnerable.
You must isolate Tor process and userland in separate VMs, or even separate physical devices. Even if the browser gets pwned, and the NIT gets dropped, you'll be OK, because the Internet is reachable only through Tor. Whonix is an easy to use implementation.
I've been ragging on Tor Project about this for years. But they don't want to frighten people by making Tor too complicated to use. You could be cynical, and say that they want the cannon fodder for their government masters. Or you could say that they think it's more important to protect the most people, rather than to most strongly protect technically competent people. I have no clue what the truth is. Maybe there's a range of opinion.