Because Jerry Sandusky is writing a book.
Ok, that in and of itself doesn't make capitalism absurd. Anyone can write a book about anything they want. In this case, it's a convicted child rapist writing a book about why he raped children (or probably arguing those kids are liars and he didn't do anything).
Now as the article linked to above notes, he won't get any money, because in most places it's illegal for someone in prison to profit from the story of their crimes, be it in book, movie, t.v. show, or any other form. But there is no law preventing other people from profiting from that story.
Other people like whomever choses to publish this book (I don't believe anyone has agreed to yet, but someone will). Because in capitalism, there is no room for morals. Sure, there may be a capitalist or two who are somewhat moral, but they'll be quickly crushed by their amoral counterparts. Because as they'll be happy to constantly tell you, the capitalists' only duty is to increase profits. Causing trillions of dollars in environmental damage? Too bad! Sexual assault and forced abortions in your factories? Cost of doing business. Firing workers when you're making record profits? Not my problem!
Now you can add to that list "giving a convicted child rapist a platform to publicly denigrate his multiple victims."
You or I, as rational human beings with some semblance of empathy, might think "hey, this guy had a criminal trial to tell his side of the story. Why does he need a whole book to do it again? Didn't the multiple victim testimonies and piles of damning evidence pretty much seal the case?"
But you would only ask that because you're not very good at capitalism. If you knew capitalism, you'd know people love to gawk at a train wreck, so there's lots of money to be made by publishing that train wreck's memoirs (ok, shitty metaphor, but you get the point). Who cares if the whole enterprise is horribly morally indefensible? There's money to be made!