If my buddy is going to replace his inner tie rod, because it disconnected and is now being dragged by the outer tie rod should he just replace the outer also? He's also aware that he's gonna need a alignment afterwards.
The alignment is the lion's share of the expense here, so why wait til the outer side goes up to redo the alignment? Ideally, he should also replace on both driver and passenger sides while he's there for better/even wear. With a decent ball joint remover (harbor freight, $10. Get the screw type, not the fork) it's a quick job.
A pair of tie rods and alignment combined will still likely cost less than a new set of front tires so why risk wearing them unevenly? 10 years isn't so unreasonable for ball joint lifespan, so it's just that time.