A new account claiming to have had 700 btc, but probably doesn't know enough hence getting scammed (assuming what you're saying is actually true). Also, thinking you could do bad things with only 100+ miners. You're going to need a lot more than that. Yeah sure 700 btc.
Agreed , this story does seem a bit out there. Someone that actually had that much money stored in bitcoin would surely be much more careful with their security.
Unless I see more proof I'm not convinced that this even happened. On the slight chance that this is legit, I'm truly sorry for your loss OP.