LCA balljoint/castle nut question

[Ezzz]

Just installed some 2" drop springs to raise up the front a little from where the po had it. When I got started I noticed the castle nut wasn't threaded very far onto the driver's side spindle/lca balljoint (pics should show what I mean). Thought the po was just lazy and that I'd been lucky driving around with the balljoint not completely seated. Happened to finish up the passenger side first and was actually amazed how easy it was. Thought I was just about done when I was lifting the jack to seat the balljoint, but even after banging on my spindle like I was trying to get it off, I couldn't get the castle nut on any further than the po had it. I'm wondering first off, why not? Second, how serious of an issue is this? And third, should I just get a new balljoint? It seems fine otherwise, and when on the road I couldn't notice it.

Here's a pic for reference of the passenger side (good one) and the drivers side (not completely seated).





Thanks
Ezzz