Actually, now that I think of it, Hive account@dan is not only failing at censoring Alice, he is paying for her to have a nice income based on double spending.

Consider what happens every time Alice is able to push a transaction through on bittrex. This happens when the public miners beat the private miners (attackers) over a given 2 block interval. Hive account@dan later comes along with his 51% attack and negates her transfer to bittrex because censorship is an ongoing process. Bittrex has credited her balance, but since Hive account@dan has negated her transaction from the block chain with all that censorship, she gets to send to bittrex again. Hive account@dan is conducting a 51% double spend attack on Alice's behalf instead of censoring her.

Derp.