People go to his website for a certain product. They couldn't care less how the site looks. Does crappy look of Apache software website turns you down from getting the newest download? How about PHP site not updated since 1999. Does their crappy site means they don't know their craft?
After checking couple tabs (that are easily accessible) and being convinced he knows his business, there is nothing more to do than either pull the trigger and buy a product/try it, or leave the site. No fancy graphics or frameworks will change users' mind. And they shouldn't. In fact, if that site would be up to date designed website all nice and clear, I would immediately think its a scam or probably software with built in backdoor, etc.
His site is fine. He is selling table planning software (that looks decent), not a web design lessons.