Pretty certain persons indicated citizens. Aliens have no lawful claim to representation, they cannot legally vote so of course this case of persons is intended to mean folks who can. Of course, probably 1000 pages of case law garbage likely have argued this point to ideological death....
The Libertarian party platform includes open borders and free flow of persons and goods.
The people who wrote the 14th Amendment knew the word "citizens"-- they used it four times in the Amendment. But when it came to reapportionment, they said "the whole number of persons," not citizens.