Drew, the thorns on a blackberry are cute and cuddly compared to those on a honey locust.
I have housed pigs in a shed, outside of which were a number of honey locust, some with some wicked thorns. The pigs had plenty of room to roam, but spent lots of time moving around the trees since that's where home was. Never had any problems, though I did try to make a point of keeping the dead twigs and branches picked up and out of the way.
I would suggest making a point to not
feed them too near the trees. There's always a bit of jostling for position while eating (even with plenty of trough space), and someone could rather easily get pushed into some nasty stuff. Even so, pigs have tough skin (they were made for rough areas, and could hold their own in the worst crime-ridden back alley), so they're well defended to start with.