Wow. Some pretty strong opinions here. To the OP, I understand and appreciate your aggravation at a potential hazard left on your property. But you found it and pulled it. Good on you. You were absolutely right to do so.
Dodge Man has said it well. There are any number of people who come onto my property to do their job.
The electric coop sent their crews to trim all brush away from their poles. They left debris, i.e., limbs dumped on my ground. Not happy about it but they fit in the bed of my truck so I picked them up and put them in a burn pile. They stretched the fence wire where they climbed over it. I'm not happy about it but is an old fence and I don't have animals as it doesn't enclose a space anyway.
AT&T came through recently replacing an underground cable. At least now I know where it is. But they killed a 15' wide half mile strip of grass that is now a huge weed strip. I'm going to make "lemonade" out of it by glyphosating the weeds and planting perennial wild flowers. If successful, I won't have to mow it any more and my wife has been wanting a big sunflower/rudbeckia planting for some time. On the plus side, they "fixed" part of my fence that had been bent to a 45 degree angle, presumably by some piece of equipment catching it as it was towed along the road.
I have a neighbor who use to let his dog pack run free. The pit bull was particularly aggressive and I will shoot him if he ever threatens me or mine again. But the neighbor understood and after a while put up a dog proof fence to contain his pack.
I had to have my property re-surveyed when I bought it as a most of the corner pins couldn't be found. They left a couple of those spikes but I found them and pulled them. (The corners are now marked with 1/2' rebar set in concrete as part of the survey.) I'm not happy with the original surveyor. He made a big mistake in the original survey. If I was the litigious sort, attorneys would have a field day at his expense. I'm not happy about having to spend $1,100 to correct his mistake (but I got the seller to pay for half of it) and now it is done right.
I'm not going to let these "slights" stop my enjoyment of my ground. If I catch somebody doing it, I will press them to fix any problems they cause. My survey is now correct and permanently marked. Where appropriate I added fence to stop any boundary confusion before it started. At least your neighbor is trying to understand where his property lines are. It would have been nice if the surveyor had picked up after himself but likely he forgot and doesn't intend you harm. If you are having to brush hog, do you have other obstacles that could damage your tires. I count myself lucky that I haven't had a flat tire from the locust thorns or busted equipment from a rock or stump. There are a lot more of those than a couple of survey spikes.
JD, I hope you are able to enjoy your property. Yeah, the surveyor should have cleaned up after himself, but he didn't and you do have choices should you ever need a survey again. If the surveyor ever comes back, talk to him. Most likely he will pick up after himself with some gentle reminding. Good luck and I do hope you can enjoy your property.