I didn't in any way suggest BAME applicants had a 'fear of failing' or there was a fear of promoting change from within, so yes, I agree, it's a poor argument.
What I was alluding to, and it was mentioned elsewhere, is that there is a stigma of bigotry and racism associated with the police and by joining them BAME people could be seen as accepting the racist bias of the police force. Why don't more BAME people join the police force? For these reasons and absolutely not because of a lack of educational attainment alone.
In a perfect world, yes, you would hope the BLM message would inspire a ton of new applicants and therefore change from within from a younger generation, but the fact we're talking about this suggests we're not in a perfect world and this stigma will be extremely difficult to get rid of.