In addition to the weird stance and thinness, he also looks like he has mange? I agree that something about him is just not right, but maybe that's because he's not my type of hog.
He looks like he might have a bad case of worms, possible lice also. By the ear notches, I would think he is purebred yorkshire, maybe even registered. Is this friend looking for a boar to breed? I honestly would not buy him unless he was GIVEAWAY priced and I had a pen to quarantine him in.
From the little I can see of the background, it looks like he is in a building and it probably has solid concrete or even the slatted concrete floors that hogs are kept on. It is very hard on their joints and the smell from the manure in the lagoons below the slatted floors, is enough to gag a maggot.
That said, boar prices are still very low. He'd have to be $50 or so for me to even consider him as a "fix -up" project. Kill hogs are in the .60-.90 range from what I have heard but most boars will bring .10-.30 lb since they mostly go to processed cooked meats and fillers so are not worth much of anything.
If they were to even consider him, it would be 2-3 months before I would even let him near any other hogs; and for him to be in any kind of condition to service a sow.
Definitely looks under weight. I dont think he has mange or lice, i think the red is from him rubbing on the cement walls. I definitely think the pig needs more food, if you look at the pig behind him in the pic they are hunched up too. I would suspect he needs wormed too.
They are definitely on a slat floor and look to be in a small confinement setting. Poor guy.