You are just making their argument for them.
The sport needs to be more accessible to these communities so that it incentivizes picking a career in that sport as opposed to whatever other avenues they may go down. There may be a star black cricket player who chooses to play football as a half-decent player (or vice versa) because there are more football clubs in his community (i.e. it's just much easier).
That's my point the situation is much deeper than a simple case of accessibility.
Its a mental and generational outlook to how black & asian brits view cricket and football.
I'm a black brit & none of my black friends my age support cricket. Some may watch - but won't look at it as a career option. I'm a unique case because of my strong west indian cricket heritage in my family & it stuck with me.
Sure cricket isn't available to play in english public schools as it is in the majority of private school (although the ECB is trying to subsidize this) - but that doesn't change the fact that most black brits view cricket as "posch/white" sport. Plus the decline of West Indies as a cricket force, which coincidentally occurred in my generations lifetime didn't help - this is why i say black brits would need a star black player to pull them back to cricket in droves.
With asians, those are my main cricket friends in UK & the large majority of them support India & Pakistan or in some cases the west indies if they were from Trinidad or Guyana. I have met very few brit asians that personally support England in cricket. The Pansears, Shah, Bopara etc etc that have played for ENG are in the minority.
So again with the default position with most brit asians to support their mother countries in cricket (the main asian supported sport in UK), just making football more accessible in asian districts won't suddenly make them patriotic and want to play for England in football.
But main point is that the theory that sport should represent the full racial make-up of multicultural society is illogical, these are social factors that sporting bodies can't control or influence to any serious effect.