Didn’t read through all the posts, but felt obliged to comment. In boundary county, you will only have state inspections (electrical,plumbing, hvac) on a new build home. It’s kinda the Wild West up there. Your home inspector is not licensed in Idaho, and it’s up to you to do research on that guy too! Even as such, in states that require licensing as well as INTERNACHI/ASHI certified inspectors, they can’t see behind walls or through other materials as part of the limitations of the home inspector. Real estate attorneys will almost always tell you that you are in the drivers seat to litigate... good luck with them... proving previous knowledge to someone else.... hopefully you see where I’m going with this. Whether he screwed you or not is likely irrelevant. I’d say get the problem fixed and move on with more important things.