I seriously doubt that people granted longer lives will fritter away their extra time watching reruns of Gilligan's Island (though some might, and it would be their business). Instead, they may well engage in longer-run projects such as ecological restoration or space exploration.
The problem, is the parenthetical. The author considers it none of his business what people do in their private lives, to the point that he doesn't consider any options wrong.
There is a common idea, which asserts that the public domain is objective, but the private domain is subjective. It's wrong to rape people, to give speeches inciting murder, and to run a red light. But in your private life, anything goes. Watch whatever TV you want, in whatever amounts. Be productive, or not. It's a matter of taste.
Now, this idea has been fruitful. It allowed us to have law and order, without curse-word-police and productivity-police stationed within our homes, telling us to expand our vocabulary and sleep less, or perhaps to stop drinking beers, or whatever.
However, from a philosophical point of view, the idea is simply not true. Choices can be wrong. Whether they are in the public or private domain doesn't matter.
Returning to the article, the author was arguing against people who feared immoral behavior. And he told them that, in the private sphere, he endorses immoral behavior as everyone's right. And his best defense against the possibility of immorality is that he doubts anyone will do it. What he should have said is something like, "If watching Gilligan's Island is the wrong thing to do, why will people want to spend their time on it?"
More on this last bit in next entry.