That's Elon Musk for you.
Never missing any opportunity to hog the limelight by making bombastic twitter pronouncements just to get free promotion for his company with no intent to deliver. What 8 hour build submarine, inflatable tunnels, deep drilling - all designed to sound revolutionary and impressive to laymen.
If the rescue team opts for something that somewhat resembles his twitter "suggestions", he gets to hype the whole thing like he's managed to provide expert consultancy on twitter through watching CNN cave videos. In this case which they didn't follow his "adivce", he's at least increased exposure and created an image of being socially responsible. Smart salesmanship, but scumbag ethics.
Thank goodness the people doing real work on the ground know how to go for a simple solution that works, i.e. dragging the boys out in an oxygenated body bag.