I've looked at their online catalog a few times.
Someone should correct me if I'm wrong but there doesn't seem to be very many southern seed companies. That outfit emphasizes southern choices altho that doesn't necessarily mean that they won't grow well elsewhere. But yes, I've given up on watermelon. Some more common garden species have regional favorite varieties. Okay, watermelon is not uncommon - just an ephemeral plant in my garden.
Honestly, a hybrid probably comes from a single location somewhere with low labor costs, anywhere in the world! No matter who sells it, it's coming from the same acre or two.
I know that hybrids are not what Southern Seed Exchange is all about. It's good to have these places with their special selections.
Steve