Because spirit birth does not matter only actual birth.
Why? Because you say so? Or are you speaking of legalities, here?
And a person's original source spirit-birthplace is of no "matter" to voters? Who says?
Why would voters want to vote for a self-professed "alien being?"
If Obama said he was born on Mars or the next solar system over -- would that be of less interest than Kenya? Why? In other words, why the reverse interest??? (And only that interest?)
Romney would say that Kolobian birth would be of greater import to him personally (than any physical earth location).