They have something correct.... If someone could maintain a double spend {51% attack} they would eventually kill the coin. Two questions comes to mind :
1. Would this go unnoticed, before Gavin and his team react and stop it with counter measures?
2. Why would someone want to do this?... Doing this gives you extra milk, but you would be killing the cow.
![Huh](https://bitcointalk.org/Smileys/default/huh.gif)
Whoever wants to do this has to be super stupid and have huge pockets to fund it. The cost to do this outweigh the possible profit to be made from it.
![Grin](https://bitcointalk.org/Smileys/default/grin.gif)