The elderly and maybe the very rural. I have a tough time thinking there is anyone rural enough who would not go for satellite internet though. Satellite TV is pretty standard in the country.
I think its just pricepoint. Dial up was like $20 or $25 a month. If someone cares so little about modern internet to be fine with dial up speeds, they don't want to spend the money for satellite internet plus the dish and installation costs.
Dial up bandwidth is of course bad, but how is latency in dial up vs satellite? Geosync orbit satellite latency is abysmal, unless you are talking about low orbit.