I loathe Whitman so I’m not going to read and think about that poem again, but you’re in luck because a lot of other people already have.
As for the other two, well, clearly Bradbury liked the title of the poem, and he was being literal about the “body electric[al]” part. The Twilight Zone episode is based on the story, of course.
As you can see, aside from the ones where the phrase is just accidental because of “body” being the end of one phrase and “electric” being the beginning of the next phrase, the references all seem to use it as meaning “an electrical body.”
It’s sure as Hell better than the ultra-literalistic title the otherwise wonderful 1980s TV movie had~ “The Electric Grandmother”. And it far surpassed the Twilight Zone version as it took it through to the actual conclusion of the story.
Oh yeah, and God bless Ray Bradbury for writing it!
This contains one of my favorite passages in all literature:
Don’t you hear them pass? hover? dance their language? telling where all the sweet gums are, the syrups that make bears frolic and lumber in bulked ecstasies, that make boys squirm with unpronounced juices, that make girls leap out of beds to catch from the corners of their eyes their dolphin selves naked aflash on the warm air poised forever in one eternal glass wave.
Your characterization applies to “Song of myself,” but we should remember than many other of his poems express an ecstatic appreciation of the world around him that is not at all egocentric.