I don't understand what peoples objection is to GG's workout tunes are (if you didn't want to know, you didn't have to ask), but everything he mentioned has a good beat for working out to, which is the point to workout tunes, no? So his tastes in music are 40 years old, BFD.
And, for the record, if I worked out, which I don't (I'm not quite the stereotypical fat slob in his mother's basement, but close), I'd probably listen to whatever audiobook I'm currently listening to, as I do in the car. (At the moment that would be Jim Butcher's Dresden Files series.)