Of course that is the point of spreading your trust around to as many nodes as possible and target isolating nodes with a Sybil attack. You can also isolate nodes by identifying the patterns that make some nodes more important to isolate than others, so a lot of nodes are isolated by isolating a fewer nodes. No P2P network is perfectly distributed.
Again I don't know what the ratios will end up being between T and 51% - T. A proper modeling has to be built.
And I doubt that is the only attack. I haven't expended more than 5 minutes yet thinking about how I would attack it. And I don't even know all the fine design points and I would need to probably know that in order to try to identity more vulnerabilities.
Also it is not clear if your economic model isn't gameable. I haven't delved in that.
For example, nodes might even pay other nodes to accept them as their peers. Remember
Vitalik's point that consensus is an undersupplied public good.
Unfortunately, altruism-prime cannot be relied on exclusively, because the value of coins arising from protocol integrity is a public good and will thus be undersupplied (eg. if there are 1000 stakeholders, and each of their activity has a 1% chance of being pivotal in contributing to a successful attack that will knock coin value down to zero, then each stakeholder will accept a bribe equal to only 1% of their holdings).
In summary, I don't want to comment more other than to say it is a complex model and I would want extensive peer review.
Edit: I want to emphasize that my comments in this thread are not to be taken as a statement of certainty (or even probability) that eMunie has a flawed security. I am presenting my initial opinion (based on very quick read of the first blog article) that it is difficult to reason about with certainty and I'd prefer a more thorough analytical review especially a formal model would be fabulous.