Not sure GBP are racist as such - not when Hamza is nailed on to win Strictly. I think they get behind the following:
an underdog, a big name, a drama llama, an attractive contestant or whoever is Ms/Mr Congeniality.
Once you have taken out those archetypes, it will be based on the edit and any known fanbase (e.g. soaps).
What you can argue is there is not enough BAME representation on telly - hence why the recent Channel 4 Black to Front day was so interesting.
I don't think Charlene and Scarlette were huge names. Babatunde, however, I'd be surprised at being an early boot because of the audience share for Gogglebox.