For instance the coast guard isn't protecting Tennessee
I'm usually polite on Facebook, but this comment is inane.
If CA were a separate country and had to support their own Coast Guard, there would just be another national border along the California border with the US, and you'd be patrolling that instead. It is indeed in Tennessee's best interests to help pay for the cost of patrolling national borders.
But the main reason this comment is so stupid is that Tennessee also depends on the Coast Guard, as they operate on the Mississippi River and other large bodies of water. Even if they did not, all that shipping up the Mississippi comes from somewhere, and the bulk of it isn't from elsewhere in Tennessee.