For people who aren't citizens of the South, I think the regional constitution is fairly clear that they wouldn't count.
There probably isn't a posting requirement though (I'm opposed to posting requirements anyway).
I'm pretty sure Siren is correct here. Per Article III, Section 4 of the Constitution, senatorial elections are regulated and administered by the Regions, which suggests that federal activity requirements would not apply. However, since TDAS and Alex are invalid due to citizenship requirements (neither is registered to vote in the South), removing the activity requirement does not effect the outcome of the election.
How does this effect the vote totals?