They’re not shocked, they’re alarmed that the left has gained such a clear and dramatic groundswell of support and that they found a flaw in a mechanism they have traditionally used to tilt the scales in favor of machine incumbents.
They are taking steps to mitigate this, I would absolutely expect them to even overtly rig the general, and everyone should be paying attention to who owns the voting machines, whether the software is audited, and how the votes are tabulated.