I agree w/Flash; If you get similar results on next test.. you have something going on. Probably not a thing to do to prevent it either. Lets just say it's 'on it's way home'.
I'll step out on a limb here, because I don't have actual experience of running one of these beyond even 100k yet
But I'd almost say that replacing the rockers every other TB change would be prudent. Rockers alone aren't too bad: I got all 16 for 150 bucks.
Mine tanked with about 80k, not the TB, but the water pump bearings... and the resulting slipped belt/8 busted exhaust rockers. Mine fell well 'outside' the expected wear and tear. Yeah, I'm 'That guy'.
Back to your higher iron; Last engine I had a test similar to yours, was immediately after the intake pipe rattled and cracked wide open.. I call it 'dusting the engine'.
Does your rubber intake from the airbox to turbo show signs of having a new intake hose in place, or show signs of being rotten? Looking from above won't show it. they rot out on the bottom..where the oil pools. I see you recently bought this rig, maybe previous owner replaced it, no way to know how long he might of run it with poor filtration. (if it was indeed a problem)
Anyway, high wear metals such as iron usually comes from cylinder walls, gears , oil pump, cam lobes/rollers. You have basically 'zero' for bearing materials, so that part is good!
But, if it was truly good and dusted, you'd show higher silicones too.. at least until several oil changes flushed it out. Silicones are present in everyday 'dirt'.
Good filtration and sound intake pipes keeps It out.
Not saying this is what is going on with yours, just be aware it could be. I'd say your chances of it being rocker/roller/cam wear is probably the culprit.
edit to add; I pulled my hair out on my whole fleet about 14 years ago! Every one of my tests came back 'high' in iron. I get mine in bulk, and it was in the new oil! Boy, did I have a lonnggg talk with my supplier!