I've never heard that definition before. The word has been around a lot longer than concerns about White actors wearing make up, and it usually means any kind of cover up, usually of some sort of scandal. ("Nixon atttempted to Whitewash the Watergate scandal, but failed.") Applying it to these problems, is a legitimate extrapolation, but not the original meaning. You have no reason to apologize, you are using the word in it's original meaning.