1. Surely not knowing could be the point? If you were accidentally prejudices for not knowing what is offensive to someone, and someone told you 'yeah well you not knowing what that meant isn't the point' that'd be wrong and unfair on you, no?
2. That would be those who criticise the BBC's problem, to me. I don't it harms the organisation, and I doubt they're that fearful of those who aim such criticism. It's a minority I'd say.