The only thing I could think of is that this player got to the lootable remnants while the rest of the group was still up on the platforms. That way, he would have been able to loot it for himself since he was the only one in range eligible for the loot. Therefore, he may not even have done this on purpose, he just clicked on the loot pillar without knowing it would lock everyone else out from the loot.

Did this player die and was battle-rezzed by any chance?

To me, this seems like an engine limitation. I guess they could ensure that the hypergate remnants spawn a few seconds later, but they can't fix anything about the range issues.