But cost is exactly the point. WW is absolutely correct to baulk at cost figures anything like those mentioned. IAG is far better served by the status quo. IAG can expand at Madrid, Barcelona, Dublin, Gatwick and more. Especially if they do eventually take over Norwegian.
I also disagree with your suggestion that the cost of expanding Heathrow should only be compared with other airport upgrade projects. The fact that entire new twin-runway airports can be built in various other countries (including those with high real estate prices) for a fraction the cost of upgrading Heathrow by one third is utterly damning. That's the point and it is valid.
If the cost of the R3 proposals was £4Bn - like Badgerys Creek - then I wouldn't object to it either. But its all-in cost including access upgrades is in the ballpark of £30Bn. That is what WW sees. So he is right. If that is the price (and we're told it is) then expanding Gatwick / Stansted instead is a far superior option for London.