Because no one honestly believes that, and because what he actually said garners more appproval from people who think diversity is bad
You think he actually -wants- to sound like a racist D Bag?
I think it's more of a case of being terrible at explaining your choices, but I guess that loving his cinematography makes me want to give him the benefit of the doubt...
As per casting itself, you do not think it conceivable that out of say a possible 500+ audition casting (most likely in England) most of the applicants were white and all the children cast just ended up being white?
All I'm saying is that unless there is a definite will to have a diverse cast to start with (which is definitely something that could be blamed on Burton, and I think he is defending his approach of that, albeit in a very dumb way), this is the kind of casting that I can see happening and without necessarily involving malicious intent.