All of the current from a lightning strike is going to be there no matter what (it came through 5-10 miles of air). If you are jamming it through a high resistance you get a lot of heat. If it goes through a very low resistance path it dumps the energy into the ground.
If you look at the extremes you can look at an old dried out tree, that will literally explode or you can look at the copper conductors from an air terminal that shows no damage at all.
All that said, I have never heard of a properly made Ufer blowing up and we have a lot of lightning strikes here.
