The line in his penultimate paragraph is telling: The idea that 3,000 state schools can’t produce a few hundred able Oxbridge students, with the right encouragement and extra support, is farcical.
That's the whole point and he's missed it. Your average state school realistically doesn't have the resources and knowledge to support bright yet disadvantaged pupils to gain a place at Oxbridge. The solution is better support for schools, not creating some sort of hideous special colleges for poor kids, which sounds like a particularly divisive way of lowering the bar.