i think he means to say the last paragraph contradicts the first: "If not for a virus, none of us would ever be born." if horses and pigs are a-ok without it,

i think he means to say the last paragraph contradicts the first: "If not for a virus, none of us would ever be born." if horses and pigs are a-ok without it, then the assertion that in its absence we would have no chance of existence seems a bit odd