I understand now that by "difficulty" you are referring to the threshold to sign your stake over. And as I told you from this start, this is not computational work that prevents a Long Range attack. One can go back and sign for some state of the chain as far back as the genesis block and pretend that signature was issued back at that time. And rebuild a completely new chain this way, because there is not computational work that has to be done to prevent the attacker from building a very long chain quickly. That is precisely what is meant by the "nothing-at-stake" problem and why checkpoints are required.

So after several pages of you trolling me, now you see I was correct. I warned you.