“Each stone was a mouth, speaking for a family”
The reference here is to the stones that members of the internment camp has spent time looking for, polishing and turning into a rock garden or a pathway. Many of these human constructions remained intact through the decades after the closure and release of the internees and in the process served to become a metaphorical voice capable of speaking about the power of perseverance and the endurance of the human will to survive intolerable cruelty.
Metaphorical Manzanar
Eventually the author comes to recognize Manzanar in the quarter-century since she was last saw it as being a metaphorical location rather than something real. Over the years it had become “more than a remembered place, it had become a state of mind” because the memory had lingered inside her mind like a real location she could never leave.
“for me it was like a birthplace”
The author compares her experience at Manzanar to that of her father. The suggestion is that the internment camp is the place where her father suffered a figurative death, but where she managed to blossom into an individual as a result of being out from under the authoritarian grip of her father. Just as her father did not literally die in the camp, neither was is the place where her mother gave birth to her, but the paradoxical experience of enjoying independence became the place that gave birth to the adult she would become.
“To the FBI every radio owner was a potential saboteur.”
This is one of those examples of a sentence that is simultaneously a metaphor and a literal statement. The context, of course, makes it clear that “every radio owner” refers not universally, but only to those of Japanese descent living on the west coast. And the fact is this probably was literally true or at least close enough to count. After Pearl Harbor, paranoia was running at a fever pitch. The intent of the statement is primarily metaphorical however, as a means of suggesting just how high that fever was running.
“He was a poser, a braggart, and a tyrant.”
The poser, braggart, and tyrant is the author’s father. In a way, the memoir is really more about the war between young daughter and the father she describes in these terms than it is about the war between American and Japanese forces in the Pacific. It was that war—the outside war taking place in faraway foreign lands—which created the circumstances that intensified and irrevocably altered the state of things between father and daughter. But it is the war between a child establishing independence from a father who traced his lineage back to the ancient samurai only to be reduced to a criminal by his adopted country simply for being born in Japan that becomes the real focus of the story.