I think that claiming an author's works should no longer be read or appreciated because of unrelated statements is a bit silly.
If someone's a serial killer (and this is a veeery extreme comparison, she's no murderer) then that serial killer should be in jail, but if that serial killer writes a ten part epic about a magic goose. you have every right to enjoy that ten part epic (and you might get some social/cultural understandings reading it, knowing that the writer's a killer, since that's probably reflected in their writing, or surprisingly unnoticable)
As for the Death of the Author thing, I think it's fair to say Rowling was actively preaching tolerance. Heck, even the biggest self centered morons will still try to preach good values, because they rarely realise they're breaking those morals themselves. If anything, it's interesting to read a work from an author whilst trying to understand how their world view is slanted. People with bad ideas get those ideas from somewhere after all.
People still enjoy Lovecraft's works, and he is very openly racist and idiotic in those, but it's interesting to see how this sad reclusive man from the days of old would look at the world and see fear in every corner.
So regardless of what you think of Rowling herself, there can still be value in reading what she wrote (unless you're bored by what she writes, or just too uncomfortable to enjoy it)
I've seen Rowling say some dumb things, but nobody should have their writing license revoked for being ignorant or bad at arguing.