It occurred to me that high-level-player killing sprees are not only a threat to those nearby, but in fact to everyone in the world.
This is because if such an event happens, J&|L will be forced to suspend the game to determine if cheats, hacks, or exploits have been involved. Even if it is not immediately clear that this is the case, it must be proven that it is not. This suspension, as we have seen, may last for hours, depriving many players of access, and potentially leading to serverwide "fixes" such as the quality reset.
However, if there is an immediate and strong response from other strong players, then it is likely that the attack can be stopped quickly. Thus, it is less likely that there will need to be a suspension, and less time will be needed to fix issues if there is.
For all these reasons, I humbly propose that should a rampage occur again, all players do whatever they can to stop it, from fighting personally to providing tea to building barricades. By putting yourself in some measure of personal risk, you protect everyone, including yourself, from the certainty of a server lockdown.