It didn't occur to me for a nanosecond until I saw the title of this thread, to be honest.
Anybody who starts shouting racism every time a person talks to, does or says anything to a black housemate needs to grow up a bit. We would end up with nobody talking to a black (or person of another race) person for fear of being called racist all the time, then where would we be - apartheid!
Nobody would think 'racist' if they had picked a white housemate, James Cosmo was second on their list from the sound of it. Would that have made them ageist?
How about sexist - picking a woman over a man?
It's all rather ridiculous an idea in my opinion. They thought she seemed rather dull, or lacklustre, so they picked her.