"There are good answers to all these objections."
There are not.
"How likely is any of this to happen? Not very"
He doesn't understand one iota of the challenges involved.
419,000 kg when finished
Let's guess a conventional ( rather than months-in-the-van-allen-belts ion ) ISP - 390shttp://www.strout.net/info/science/delta-v/intro.html
suggests 4.1km/sec required
You would need something like 16,000,000,000 kg of fuel. 16 MILLION tons.
A fully laden Saturn V rocket on the pad carried 2,708 tons of fuel. It had a max payload of 118 tons.
Let's go optimistic - lets say it's a 1600 ISP Ion engine.
The requirement then is just 5,000 tons. 42 Saturn V launched laden with Xenon.
Someone please check the numbers on that - they may well be orders of magnitude off - but they do, to me at least, seem to be in the right sort of 'bloody stupid idea' ball park.
The phrase ' hand waving over the details ' has never been more appropriate