Sam Riggs left the country about ten years ago...last I heard, he and his school was in Belieze...doing the same thing he always did. And apparently still not lacking for students willing to go all the way down there to get fleeced.
Ag schools pop up every year, and last a couple of years before going under. Many claim to have been around for eons, claim that they can get you hired...claim the moon. Usually a two place ag aircraft, and for a few thousand, will give you some valueable "turbine time." Tell you it's sure to get you hired.
It's not.
Ag work is great work; it's truly flying...but be careful of getting roped into the "dream" that it's something you can walk into after a short school. It's not. Most jobs are not entry level positions.
As for "training" to tow banners. It's not rocket science, either...in fact, it's sleeper type work. You pick up the banner, you tow it around at slow speeds, drop it, go get another. Don't get roped into paying someone to "train" you or "certify" you to fly banners. It's a ripoff. Much like many of the ag schools.
Be careful about promises regarding teaching at the ag school, too. If it's difficult to get into flying ag...what kind of experience do you suppose is appropriate to teach people to fly ag? If you survive your first thousand or two hours of ag, then consider looking into teaching it...but that's still entry level experience. Look at it this way; do you want to be taught to fly ag by someone with no experience? Take that question seriously, as though your life depends on it, because it really does.
Typically your first few years doing ag are spent loading and learning the business, eventually flying rinsate and big open fields, and eventually doing jobs on your own...but not really something you take 20 hours of training to do, and then go to work making six figures. Or anything remotely close to it. Not telling you not to pursue your dreams, but be careful doing it, and spending your hard earned cash for promises that traditionally don't add up.