Kirkpatrick's best years are behind him now, and his availability and productivity have dropped way off over the last couple of years. Bringing him in for "competition" just takes away a camp roster spot for someone who may be a better bet in the long run.
I've had my eye on Throckmorton for a long time. He had a terrible senior bowl, but he's long on experience, and has played at multiple positions. At the very least, he would satisfactorily make up for the loss of Haeg.