the point is, that we shouldn't be able to be flagged on TI, it should be neutral territory not contested.
Plenty of people that are on PvE servers like to engage in PvP sometimes, as you apparently can tell by the number of people flagged on the island on your realm. Avoiding flagging yourself is usually fairly simple, but mistakes do happen, and you may die, and you may need to wait for the 5min PvP flag to disappear. Just be a bit careful about what you're clicking on/targeting and you shouldn't have any problems. (AoE attacks will not flag you unless you have a flagged player targeted)