My theory on the ending

I don't know why nobody has said this but I belive when mcrvies dies garraty enters the Olson state. that's why he keeps walking. he gave up but he found that new world. his subconscious made him keep going. I assume until everyone stops him as there's no way they would let him just keep going and idk why people think he walked until he died. He went mentally insane as it's like war trauma as the books an allegory of vietnam