If ISAs don't pay out, then hedge funds will not be willing to pay as much to buy them. So at least on that point, the mere fact that they're sold off doesn't cause any misalignment.
Had the dumb manipulations not happened, loans are actually quite straightforward to value, so I would be shocked if whoever was purchasing the ISAs didn't have at least a "much better than HN" view into what they should properly be worth.