He may release them. With bee swarms it’s common practice to starve them for a day before putting them into their new hive. That way they don’t immediately swarm/leave again. Wouldn’t be surprised if something like that works with hornets too. Starve them a bit then release them in the woods.

FYI no need for poison. Just use dish-soap water. (Works for bees at least and their carapace is the same material as hornets/wasps)