Non-sequitur. What Weinberg said is "I don't see why the mind can't be understood, in principle." That's the attitude any scientist must take. It has nothing to do with metaphysics. Either the mind is understandable or it is not. Until the mind is proven not to be understandable--a very tall order--we must proceed as if it will someday yield to our probing. To do otherwise is to abandon science.
And whether the mind is understandable or not, I don't see how any of this has to do with atheism. If the mind turns out to be made of only springs and gears, that has nothing to do with whether God exists.
You've missed the point. I'm not disputing that science can unravel brain function, I'm asserting that science can't unravel whether or not the laws governing brain function are personal.
To assert that there are "impersonal laws" isn't necessarty for science, it's a question that science can't answer, therefore Weinberg and scienctists would be better served by wearing their agnostic hat and shrugging their shoulders about nonscientific questions.
"It's not my job," isn't that hard to remember.
Scientists presume the right to throw sharp, nonscientific elbows, but are quick to cry foul when nonscientific ideas intrude on science.