He'd be willing to let everything his colony had established be destroyed along with all its people to encourage some other colonists he knew nothing about?
What was the point of getting killed at the Alamo? Nobody survived, but the senseless defense sent a message.
That's among the most common reasons to put up a defensive fight: to be remembered. Generally, you don't get attacked unless the attacker is certain of his victory, after all, so the defense achieves nothing in pure tactical terms.