That's just it though, an attacked would not to have any stake in BTSX.. or barely any, just enough to be allowed to run a delegate. Then he maybe he spends some money convincing people to vote for him or giving giving back 100% of transaction fees to those that vote for him, or whatever. Given that people can vote for multiple delegates, a lot of people will vote for these delegates who are willing to work for free. Once the attacker gets the bottom 51% of delegates, he locks down the network.. and 51% attacks and you hurt trust in Bitshares, even if you do fork the blockchain.
If a single attacker went this route it would be akin to a public official getting elected to 51 different offices simultaneously. Yes, it would be technically possible to create 51 delegate IDs and contrive to have them all elected. But damn, I can't imagine the time and effort involved. Not to mention the end result being a collective shrug and a fork.
It is also conceivable for a person or group to coerce 51 delegates through force or other means, but again managing that would be a nightmare. The global logistics of doing this are mind boggling. Perhaps a government, but even then jurisdiction is going to be a big problem. And good luck doing it quietly. That is a lot of victims and a lot of laws being broken. And still, the end result is a fork.
Not going to say it can't/wont' happen. But the impact/probability ratio is very, very low. And if user assets are not at risk, how many are really going to care? It's kind of like the response to the 51% attack in Bitcoin. 51% has been hit by a single entity multiple times. People are still using Bitcoin.
We are talking about an investment climate where folks are exposed to defaults, bail outs, bail ins, rigging and rampant systemic corruption.
If the worst that can happen are some minor disruptions to service (not even sure there would be a disruption) while delegates implement the fork most investors are not going to be concerned.
Which pretty much negates the whole point of the attack.
Again, I think this is a valuable dialogue that should be captured and marketed in the FAQ or similar.
"What happens if 51 delegates collude?" is going to be a common question, no matter how small the likelihood of it actually happening.