I feel that it's truly a shame that a man died while doing his job, that laying alone bleeding out on the concrete unknown to anyone is a sad scenario, one none of us would choose as the way we want to leave this life. It's a shame that the driver, providing he's basically an average type of person, will have this incident on his mind and conscious likely the rest of his life. Again, not a situation any of us would choose.
As to blame or fault, I don't know. Sometimes accidents happen that carry extreme consequences. Sometimes smart people do dumb things, vigilant people lapse for one second. And that second can define us or affect us for life. I believe you or someone else mentioned that the ladder was damaged, that guard made a choice to use it anyway. Something you could do a thousand times and no consequences. But just one time that a chain of events lined up and this was the result. Doesn't make the guard dumb or wreckless. He did not go up that ladder intending to die, he trusted that another person wouldn't be moving his truck. We all, everyone of us take things for granted, we all do stuff that after we say to ourselves, damn that was dumb.
Safety from an individual standpoint is accountability. Did this driver know he had a top seal? If not, why didn't he? That could explain taking off after bottom seal was cut perhaps. As I said earlier, myself, when I pull up to a guard shack, check in, whatever, the first thing I do is take note of how many people are working. I make sure that I get a good look at the individual I'm dealing with. They walk back to cut a seal, bang on the trailer, the key does not get turned on until I clearly see that person is away from the truck. The truck does not move if they are walking alongside of it, even in plain sight. Were there 2 guards maybe, then until I visually confirm where both individuals are and away from my vehicle, it doesn't move. My truck is turned off the moment after the brakes are set and not started until I know where everyone is. This is a process I do because of having been on so many different shipper and receiver facilities throughout the years where things are done slightly different company to company. If I completely lose track of someone, I will get out of the truck and look.
UPS has it's own system for inbounding/outbounding. I rarely see it utilized. I do a DOK every month on something that basically exists in theory. Honestly, that does not matter to me as an individual. I have my own method that supercedes any other. I will gladly comply with the UPS method if I ever encounter a guard that actually adheres to it, but I will still rely on the way I do the process.
So all that being said, I don't know where the blame lay. As often things are of this nature, it sounds like it wasn't a single action that produced the end result. The guard made a decision to use that ladder, not check keys were pulled or alert the driver he wasn't finished. The driver possibly wasn't paying much attention to the guy, didn't make sure he knew where he was. Didn't wait for the bang on the side of the trailer like a lot of guards do after cutting the seal. Could speculate on and on and point fingers all day. Doesn't really matter, it doesn't change that a man is now dead. In the end, it's personal accountability for how safe you want to be and taking the necessary steps to do what you can. If I ever were to hurt an individual or worse at a check in situation, I won't blame the company or the guard, I know that it'd be because I didn't do the process I personally use. That's my way of thinking about it for right or wrong.