In case you still have a problem...
Draft them (metaphorically) into a masonry force. Have them build a massive execution tower, a dozen z-levels above ground and a score below. The tower will be used to see how deep a goblin needs to drop to get it to burst into Xgoblin skullXs and Xgoblin meatXs and such!
Then calibrate it with your next migrant wave and any leftover idlers.
I want to try something like this, but moving caged goblins seems to release them. Can't figure out a way to move them to somewhere to let them drop..
You don't move the goblin, you move the cage. After the tower is completed, you create a narrow strip of animal stockpile that only accepts goblins (or whatever you're going to toss) directly along the edge. Then you create an activity zone that is a pit that is out over the edge in empty space.
Disallow goblin cages from being stored in any existing animal stockpiles, and the dwarves will haul the cages up to the top of the tower (or to the pit room).
Once you have a few cages up there, hit the "i" to interact with the zone, "P" for pit, and start selecting non-thief goblins.
(Personally, I always make sure that any animal stockpile tile is directly next to / orthogonal to the open-air over the pit. Helps reduce escapes, even for thieves.)