That said, the point of the thread was not so much about my particular case with this book but about discussing if someone should be offended for the points of view of characters in a book, even if they are the main characters.
My general thoughts: Jim has made it quite clear that his intention when writing is to evoke emotional responses in his readers. In fact, to quote the man himself:
I tell giant, complicated, long-term LIES for a living, man. People pay me to manipulate their emotions--to make them laugh and cry, to cheer for the good guys and to hate the bad guys.
On the one hand, the fact that your husband is reacting emotionally to Jim's writing could be seen as a positive. On the other hand, the fact that it makes it harder for him to "cheer for the good guys" makes it a negative.
In and of itself, I would say it's OK to be offended by a main character's negative traits. What I consider more important, however, is how one chooses to act after taking offense. And before making the decision of how to react, I would recommend taking a moment to try to figure out why the author made his main character(s) offensive.
If, for example, the cause of offense seems to stem from the author's own prejudice, I could see how reading the remainder of the book could be problematic; such an author is unlikely to change the character's behavior, taking away from the reader's empathy for the nominal good guys. As others have mentioned, there's also the possibility of the author being driven by a desire for verisimilitude: if people have historically reacted in an offensive way, having the characters not react that way runs the risk of breaking the audience's willing suspension of disbelief.
Given such circumstances, dropping the book could be considered a reasonable choice - why read something you won't enjoy? On the other hand, I've always enjoyed the argument that fiction should not only entertain, but also educate. Personally, I could see myself still reading a book even if I find the protagonist(s) offensive, specifically to teach myself to better empathize with people I don't agree with. It's always easiest, after all, to appreciate people who think like us.
There's a third possibility, namely that the author intends to address this offensive quality, and so, needs to first establish it, in order to incorporate it in the protagonist's character arc. I suspect that's the direction Jim is going with the racism. In such a case, denying oneself the opportunity to see how the situation will evolve would be a disservice to both the author and the reader.
TL,DR: I believe one is entitled to feel offended by a fictional character's actions or views(fiction, after all, is about evoking emotional responses), particularly if the guilty party is a protagonist, but I don't believe taking offense would be reason enough to stop me from reading a story.
