It sounds like EA did not think out their zone properly. Myself I think the line to cross for direct intervention against individual players is somewhere around duping items.
Exploit Early, Exploit Often.
Get banned.
Also, why is it so criminal of a studio to not allow the entire MMO economy get thrown out of whack, just because a couple of smart kids figure they can exploit an aspect of their game? I think it's good that the game sets an example of "if you know you're doing something wrong, you're gonna get banned" - setting it up so that you can 'tip'(?) the map by having people on each side for the purpose of looting a chest is pretty obviously exploiting a game mechanic, and not really something you can plead innocence on. They were warned, they were suspended. Done deal.
I don't support this whole "they should've thought this one through, so they should never have banned them" - yes, maybe QA should've picked up on this, but some things slip by. Does that mean it's OK to do it? Nope. Does that mean it's not OK to prevent it from continuing to happen before they can patch it out? Nope.
If someone exploits, you stop them from doing it, then you stop others from being able to do the same. Again, this was never something one person could do alone. They were more people in on it, and even on opposing factions. If you say "well, sometimes factions need to work together for the better good", then you're not getting the whole meta-game thing. If you're exploiting something on a meta-game level, it ain't OK.