I suppose, given what he had written, that he planned to keep on kidnapping little girls until his harem was full. Prison would not be kind to him.
I did try to read the entire manifesto, I really did--but, well, got bogged down after the first page or two. But from what I can gather, it wasn't just seven wives, but 49 (each of the 7 wives were to pick 7 sisters).
He's going to end up in a special unit, just like Dahmer. Dahmer didn't last very long after he requested he be let out of the special unit. Nope, it's not going to be nice for him in the Big House, not at all. And it's no skin off my nose.