It takes something like Ebola, or at least the world’s worst STD or UTI to make urine infectious.
Any box I see that says “clinic” or medical” or “biological” doesn’t get opened. But it’s safe to go through ordinary shipping and it’s safe to sit there until it gets picked up again.
You are obviously either experienced in handling medical items or ill n the medical field yourself. This man was neither, so he may have opened the box not knowing it’s contents.