At 650Kv nearly every thing becomes conductive and it there is any dirt and/or body fluids or oils on the surface of the device then the surface of the device will be the closes thing and it will conduct along the surface to the operator or even inside the device and destroy itself and/or the cell phone.
"elecricity takes the path of least resistance, just because it can jump what 8 inches, doesn't mean it will. "
Not always true it depends on the conditions and where the charge build up is most concentrated, you can't reliably predict where it will discharge at 650Kv with a hand held device.
Then there is conduction by capaicitance.
Most materials have a dielectric strength of only 1Kv to 2kv per mi maximum, this means that the walls of the case would have to be in excess of a 1/2" thick mininum.
And that is not even factoring in 50% for safety.
Yes some exotic materials are rated at around 5Kv per mil or more, Have you priced those lately?
Look up some Tesla Coil pictures that are in that voltage range and you tell me how it is feasible or practical let alone even possible to produce those kinds of voltages in a space less than or equivilently the same as an IPhone .
I wish the guy lots of luck as I love playing with Very High Voltages.
I have much experience at this type of stuff up to about 100Kv or so.
What happens if he doesn't make is $100,000 donation goal?
Will he have to return the rest ?
Looks like a scam to me.