Optimal fail. That Jim Sonnier article has been torn to shreds all over the place. Relying on an antiquated article that holds no water pins you as exactly the type of misinformation dispenser to be avoided. Hey, I've done it too, but taking some random second-hand account of an event and using it as fact is a great way to get your foot kicked down your throat.
For the record, I would love to see a 7" Betta Splendens. I've tried every trick in the book to flush out a shred of evidence that they have ever existed. There is nothing. The closest I've come are the giant fighter plakats we're seeing around these days and their body length certainly does not exceed 4" if it even reaches that. I know it's hard to let the dream go, but there's no Easter Bunny, no Flying Spaghetti Monster and no 7" Betta Splendens. Sorry to break it to you in your moment of zeal.
The bettas in those pics do not exceed 3". When you pore through the internet looking for evidence of giants, you'll quickly learn to note various morphological characteristics. Seeing the currently available giant plakats will also be part of that knowledge base. After months of trying to track down a "True" 7" Giant, you'll have to accept that the reason you can't find them is that they are not real.