However, there is a possibility of this feature being used wrongfully, therefore we are focusing to make sure these type of problems don’t occur as much as possible.
That's the part that interests me: how exactly will they implement it?

Minimum number for VTK join group together. Friends, FC, etc. Boss dies or is nearly dead then VTK everyone else. No loot for you.
_ Probably can be minimized by saying no VTK in combat, while loot being rolled, or while a spawned chest is unopened.

Clear to last boss of dungeon, VTK to make room for friends in the queue. They get 5 minute tome rewards.
_ Cooldown on VTK perhaps. Doesn't completely solve if the friend can be reasonably sure they're first in the Join Party in Progress queue.

Stuff like that...