Well... I have had extremely skinny resell projects. The 'problem' they cause is encouraging aggression in other horses. I have seen horses that get along with most anything adopt a 'cull the weak sucker' mentality with a newbie 'rescue' type horse.
The weak newbie is 'not okay' and other horses may pick up on that and freak out about it a little. So I can well imagine that their unhealthy project might not integrate well in a group.
Newbie skinnies may also require 6x/day feeding wet, wet alfalfa, bucket loads of TLC for feet, much, much grooming and cleansing for monster scurf/scrunge/rot, etc, copious plastering of wound ointments, bandaging, special handling for the mental quirks than can come with neglect, and mucho $$ for omeprazole, chiro, etcetera, etcetera, you get the idea.....
So if these folks in the CL ad thought they'd just do the beast a good turn and get it some groceries, they may have walked into a much bigger deal than they bargained for.
I agree, I do not assume the guy is lying. He said he bought him with the intention of fattening him up but is in over his head. Most of his other horses are in good weight and the pasture looks full of grass. The horse could have other health issues as well. The owner stated he thought the horse would be easy to fix and like you say, a horse that thin needs special care, such as small frequent low-sugar feedings, vet care, farrier attention, and I would keep him totally separate from other horses until he gets some weight and strength.
I hope the owner is not the cause of what looks like founder in that horse, if that's what I am seeing -- but I am only acquainted with founder in online photos. Is that why they are so curved or can they get that curve from simple lack of care?
As for herd dynamics, I thought the owner was saying the other horses were picking on the skinny horse. I'll have to re-read that ad.
They get elf slipper feet from lack of care, but usually the feet are getting a bit long in the toe once you see the curve. The CL horse has quite a dish in what I see in the pictures as a relatively short foot - but the pictures aren't the greatest, they could have sawn off the fronts of elf feet which is often done as the first step in getting the feet back. At any rate the feet are a big red flag, the horse needs quite a bit of care.
He has this horse which he says he just got to fatten up but he also has an ad with horses in various states from fat to thin and wormy looking and also advertises that they have horses to sell and mares "about to pop".
I'm not sure, based on the looks of the other horses, several of whom look to be in pretty rough shape, that he has not had this horse for a long time and is in over his head and now must make some excuses and get rid of some of the worse ones.
It seems to me like this is a case where animal control does need to be involved and find out the real story, before we hear about another pile of dead horses somewhere.
Looks like it was posted and flagged for removal on April 30 once already, googling around. Fella is selling alpacas and all sorts of stuff. Well, regardless of the backstory the horse doesn't look good.