Marquez's bond with Castro doesn't disturb me at all. I can separate an artist's work from his politics or his personal life. In college, I remember a woman who hated Shelley because he was mean to his wife. Who cares? They're both long dead. But his poems live on, and we should be able to appreciate them in and of themselves, without letting our opinion be colored by how we feel about the author. The same applies to Marquez.
Gabriel Garcia Marquez may be more widely known for his novels, but he spent a great deal of his life as a journalist, writing non-fiction for and about his South American culture. As he grew famous, he gained more and more access to the movers and shakers in politics and entertainment, allowing him to broaden his range of topics. Simply because he knew and conversed with men that are deemed traditional enemies of the United States shouldn't color Marquez's body of works.
Their bond or relationship was a personal matter and it does not affects my opinion about his books. His work has nothing to do with his personal life whatsoever. Although my opinion about him as a person has definitely changed but for me, his work remains the same for me.
Even if I did read Gabriel Marquez's books, it would not effect me in any way of who a person has a bond with. I take most everything I read with a grain of salt anyway. I also respect their opinion, even if they do not necessarily agree with it. If I truly did like what someone had to say, I would not buy their books. It has to do with what they write, not who they know.