This is driving me crazy; there has to be some kind of...thing in there. A weird music track plays... Wait... I have a theory.
Maybe it has something to do with the event? If you remember, at the end of the event, you will get mail about the chevins were giving items to the gree. Why the heck would the gree want colicoid eggs, rakata silverware, and krayt dragon pearls, etc. maybe as an offering?
Does anyone have a level 50 who has not finished the event, so they still have some chevin junk in their inventory? If so, try to go in. Maybe something different happens.
It's worth a try.
Perhaps it is related to the chevins and the "dagoba cave" together like this:
1. you need to enter with a weapon to the cave + you need to have something of the chevins.
2. why not try the chevins weapon that were for sale during that time:
(the 3 yellow ones are the lvl 50 items)
and the fact that its only on 16man doesn't matter, you can do 8 man, and after the first boss change into 16man, clear the trash and enter the cave.
i would love if someone with one of these weapons can test stuff in there
maybe even enter with the broken speeder from the event and it will fix it!