I would imagine to take it down would be easy enough . If the lines going up were plastic ,woven carbon fibre /whatever with a line up one side and down the other I doubt lightning would be attracted . Lightning wants a quick path to ground . adequately insulated tethers would not offer it that .
The hydrogen in the balloon would not attract it at all and it would need a strike to do any damage, so what is there to strike . You could probably poke up another high point a couple of hundred yards away to attract it
I watched them build a test version of this on a alternative energy TV show a while back. Very entertaining.
It's a completely stupid concept! Well actually it's a great concept, but its a completely stupid implementation.
Electrical power generation can only be feasable when the cost per watt is low enough, and that cost per watt includes installation, maintenance and longevity. Efficient reliable generators are heavy as are their shafts/bearings etc. Trying to make a generator light will multiply its price many times over AND reduce its longevity.
That factor alone kills any flying generator concept, then you add the high probability of catastrophic failure within a few years from any nasty storm condition! Even heavy cheap ground based windmills have a 20 year payoff period. So a flying system will have much more expensive rotor, and generator, and specialised moorings so even if it never breaks it will have maybe a 50 year payoff period? Now add the problem that it WILL break and probably quite soon.
It's one of those things like flying cars. It sounds like a great idea until someone with some common sense raises all those valid points... It will never be more than science fiction.