Ok, that explains why the attackter had to wait every 20 blocks for a real block to show up...
Since the difficulty is sky high now, once we're at 20000 for the hard fork, it will take nearly forever to revert back to lower diff, wouldn't it? What is the max diff reduction now, 3%?
Could make sense to either start with a new blockchain then and honor all blocks up to whatever block it was were the truoble started, or allow for a faster diff correction downwards.