Because that does not protect from "Greed" skill. It circumvents all restrictions which is why so many thieves, bots and players alike, use it all day every day, especially during these kinds of events. The mods just need to alter the data files for the ksill so that ownership applies to the killer of monsters for longer time and change greeds ability to cheat the system.
im pretty sure i remember being in my own party a whole bunch of times with both the 2nd and 3rd options set to take/individual and seeing people still try to greed my loot but not be able to for about 10-20 seconds. i know for sure there's a window because i have countless memories of random people spamming greed over my loot like idiots and still not being able to get to it since i had those options checked.
the only way this wouldnt still be applicable is if the coding for it was somehow altered with any one of the various patch notes we've had since i last had one of those experiences. could've also happened during the new UI party window maint. been a while though since i even ran into anyone that dick. every time i've been down in low ti, most people just walk by. juperos same thing.