Highly suspicious refusal
The refusal of the Irish DPC to look into this reeks of third party influence - there is no way this DPC acts independently, at least not as far as I would judge from events so far. The idea of a DPC is to protect the weaker parties, the consumers. At least, that's the theory. Instead, this DPC has been acting more like a Banking Ombudsman, who doesn''t exactly appear to work on your behalf either..
Alternatively, maybe the DPC is using this post as a stepping stone into industry. If I recall correctly, that's what the predecessor did - could explain a few things..
Well done Schrems, but it may not have made you popular in the US..