ok. The highest difficulty being the 'Chain with the most Stake involved' is nice for sorting out chain forks on the valid chain. But I don't think that helps with the 'bootstrap' scenario, as an attacker can fake as much stake as he wants on his 'fake' chain. 'Fake as much Stake'.. lol..
In crypto, a stakeholder has to prove that he has the private key to his stake when he wants to do a transaction. You can't insert a fake block where everyone sends their coins to you, because transactions need to be signed with private keys. The NRS would detect and ignore such a block.
But this is not what you want to do, you want newbies to see a complete fake chain.
Because each block contains information about the previous block, and you need to sign transactions with the private key of the account owner, you would need to alter history all the way back to the genesis block and create a new one where you have the private keys for creating a fake chain.
Since GENESIS_BLOCK_ID = 2680262203532249785L and all initial transactions from genesis account are hardcoded in Genesis.java, I don't see how the attacker could succeed. All he could do is create a Nxt clone.