Have you read the patent? It's about how their platform works, not how the underlying open source tech works, and i don't think that it even mentions blockchain once because it's the underlying tech, not the platform itself. And this is a business based on their platform so it's perfectly understandable to have a patent for it.
But i am just speculating, please correct me if i am wrong.
Correct, I read it too and I don't remember reading about blockchain in it. I don't understand why, maybe because they can't patent the ethereum's blockchain? It make sense if you think