As Flattr 1.0 did not get any traction, my guess is that they went with AdBlock Plus creators (Eyeo) just because Flattr run out of cash and Eyeo was the one who offered to invest and later on to buy out. Simple math. Even though I'm not fan of what Eyeo have done in the past, fact that old team was able to continue to work on this, makes me hopeful, that this will not turn out to be some sort of malicious or grey area project. But time will tell.