According to Dictionary.com, the word "ignorant," means the following:
lacking in knowledge or training; unlearned; lacking knowledge or information as to a particular subject or fact; uninformed; unaware
To say that the exclusionary views that Donald Sterling expressed to V. Stiviano are "ignorant" abridges his responsibility for putting forth those points of view, patting him lovingly on the head and saying the equivalent of "Aw, bless his heart. He just doesn't know any better."
However, based on his comments Donald Sterling is very clear on what he thinks and how he feels about minorities in general and African-Americans in particular.
Just know that it is highly unlikely that Sterling has a lack of knowledge, information or training when it comes to interacting with minorities and judging each person on the content of their character as opposed to the color of their skin.
Sterling functions within an industry where he has had the opportunity to interact and engage with people of all creeds, colors and nationalities, so no one should give Donald Sterling a pass when it comes to his exclusionary viewpoints.
If you haven't been privy to the controversy surrounding Donald Sterling, check out the following articles to get up to speed on what's going on:
Huffington Post Blogs: Donald Sterling Has Been A Racist For A Long Time
The Washington Post: NBA probing alleged recording of Clippers owner
LA Times: Magic Johnson blasts Donald Sterling