Cutting a business off from the financial system seems like a fairly harsh punishment for plagiarism, especially when there are other routes for a remedy. We may never know if that was the reason, though, so it's hard to measure whether justice was done or not.
I suspect that one of the sites they plagiarized which accept PP donations/subscriptions asked PP to take them off or risk the large news company switching to another payment processor.
Well, there's plagiarism and then there's impersonating a well-known (admittedly in niche circles) brand to make money. I think they made a good call here.
So, rather than using our existing copyright / trademark system to handle cases of brand impersonation or stealing content, we're just going to rely on payment processor companies to punish people? That sounds like a really bad idea.