This has been tried multiple times for this exact convoy and I made sure that it was not simply a case of somebody finding the convoy beforehand and the dead bots despawning before I arrived. How I know this is that one time I was exactly next to the convoy spawn point and I lost connection. Upon rejoining the convoy appeared - godlike timing - and no bots were around. There was not enough time for anyone to kill them, let alone for them to despawn in the under 30 seconds I was offline.
I then tested the bot spawning of this convoy over the course of the next few hours and managed to trigger it multiple times, both by reproducing the conditions I first encountered - logging out and upon relogging the convoy appearing - as well as walking away from it and having the event trigger while I was a little further away. In all cases I was the first person to reach the convoy.
Sadly I could not try it more than a few times due to the server being full the entire day and so the spawn chance of that exact spot was very low. I'm surprised I even got it to spawn 4 times with so many players online.