Is nihilism the logical extreme of atheism?

[Mudhammam]

Yes, brains *are* "sensible objects performing material processes," which produce meaning.

Asserted without proof.

Clarification: *My* brain projects meaning on to the world. Maybe yours doesn't.

All you mean by the additional observation that brains, "like all other physical things have no meaning," is merely to admit that there is no objective meaning given to physical (or your "non-physical" processes), i.e. existential nihilism,...

my italics. You're putting words into my mouth, ...but at least you accept that the physical cannot carry meaning.

I didn't realize your "non-physical interpreters" didn't involve a process, but since you can't actually say anything constructive about their substance or functionality (probably because you have no basis for their existence), that's understandable.