Weight scale ticket

If you go back to the first few posts answering your initial question you will find the answer to that question: "What do I do about this"
#1 It's still his responsibility. Yes I know it sucks, but it is what it is.
#2 A Cat Scale ticket could prove that the "load shifted", if indeed it did. Then you would have a leg to stand on in court. And if the load shifted then they would write you up for unsecured load.
#3 I think you have no option but pay the fine and learn from this. Sealed or not it is your responsibility to safely transport the load. You need to monitor your load the entire trip and when a problem like this arises a driver should call their company for guidance. Companies have a procedure to break a seal and re-seal it. This happens all the time with mechanical issues, accidents. etc..

yes you got more than that and there was a lot of coulda, woulda, shoulda, but you asked for opinions and ###### you got some!