The solution is for ICs to stick their necks out, go over the product manager's head, and ignore the org chart? Not get a new product manager who cares about the product?
If you force every little bug to go through the product manager, you take time away from the PM to do big picture things by forcing them to track every little thing that's broken, and create a lot of friction for even the littlest bug to be squashed. This fosters an eng culture of "not my problem," which leads to bugs slipping through the cracks for years.