I do mean SD STB.
I already have a "Free for Life" SD STB on my account. If I upgrade I spend more much more money for something that rarely gets used. Think of having a TV in a guest room and you've got guests that come over maybe once every 6 months. Not really worth having the extra $16 a month (or $192 a year) just to have the convience for 4-5 days a year.
Since I have a SD STB that doesn't cost extra, that's where it's located.