First he said he is looking for the spammy EMDs:
Then he said that if you know of any, send them to him on Twitter:
He went on to add that there is nothing particularly wrong with EMDs, exact match domains. There is something wrong with spammy EMDs ranking well in Google he said:
So it looks like Google may be working on rerunning the EMD penalty from 2012 again, sometime in the future. When exactly, no one knows.