The children of Israel didn't strike them, because the princes of the congregation had sworn to them by Yahweh, the God of Israel. All the congregation murmured against the princes.
"Servants should be taken in the most pejorative sense here. As woodcutters and water carriers the Gibeonites will perform only menial services (see Deuteronomy 29:11)." [Note: Woudstra, p. 164.] 