There are multiple concerns in the comments on blocktrades original post if you care to read them.
Blocktrades answers all of them.
The attack vectors are few and far between, and most of them are extreme edge cases, and even then it appears as though the code being implemented will prevent those things from happening.
Just like any other blockchain, the longer that block has been on the chain the more secure it gets. This code is trying to make the most recent blocks more secure than they were before.