I was under the impression that the double-spend would still get picked up before it could actually cause any damage, but again, I didn't spend much time digging around in it once I'd realized that DoS was possible.
Picked up by who/what? The nodes are the network, so if you control a majority of nodes, you control the majority of the network. In any case, what all of this means is that, like instant-x, zero-time has a constant probability associated with the success of a double spend.
What does it take to control a majority of the network? Not much. Unlike instant-x, no collateral is required to be locked up, so you don't need to buy a bunch of VNL, all you need is a bunch of IP addresses.
Double spends are always possible with block chains if you control a majority of nodes, but from my understanding, you don't need a majority to effect a DoS on the ZT algorithm and to clarify again I ceased by investigations here
In the case of simple disruption or a DoS, it appears to me that you do
not need a majority and the double spend would be resolved by the usual confirmation processes.