I personally think that jotting down passwords physically is worse than saving passwords in a good password manager. Now, there are a few good ones, like 1Password[2].
So no, I disagree with this security guru's advice with the exception of 2FA recovery codes.
[1] https://en.wikipedia.org/wiki/List_of_password_managers [2] https://en.wikipedia.org/wiki/1Password
Can malware or a MITM attack compromise connecting to a password manager? It seems like anyone anywhere could gain access to the password managers severs(exploit) or my computer (malware).
For paper password, someone would need to know my address and then break into my house.
I personally just use memory.
If you get infected by malware then it could just grab the password as you type it anyway; if anything then using a password manager is slightly more secure, since browser integration goes over an authenticated connection that is harder for non-root applications to intercept.
If you were good at securing physical objects then you could just lock down the computer instead, and stop bothering with passwords.