They were cutting the tamper seal off. That is a disposable metal part that sells for a few cents. It is supposed to be removed destructively, and authorities do it all the time for inspection purposes, document the serial number of seal they removed, and tell the shipper what the new seal is. Sometimes its a lock, but most shippers don't do that since it is a hassle to get the keys to the receiver, and customs will cut your lock off. The act of sealing the container after inspection makes the owner whole.

While it is "destructive" in a very strict sense, it damages no property in any relevant way.

Any shipper anywhere on earth is well aware that their container can be opened by the authorities at any time.