Nothing he says is really controversial.
We keep using more energy and stuff, eventually we will need to get it from off-planet.
It would make sense to keep earth habitable - it is prime real estate!
It may be 100 years or 500 years in the future, but the logic is very clear.
By then we are likely to have skyhook type elevators to orbit.
The "waste" products will be valuable by-products in orbit.
It is silly to assume space technology will not have made any improvements in 100 or 500 years.