It sounds like you're doing a great job. Frequent gentle handling, veggie treats and talking to him softly are all great ways to show him he needn't be scared of you.
Many pigs do stay skittish to some extent, no matter how long you spend socialising them - it's an instinct which saves their life in the wild as they can react to and run away from predators. But most pigs do at least get the the point where they relax once they're settled in your lap, but they will always run away from people walking by and from being picked up. It can just take time.
Where have you got their cage? Some pigs are a lot calmer if you have it up on a table rather than on the floor. The world doesn't look so big and scary to them when they're higher up and nearer the people. Also (and it's not something I like to do myself as I prefer to earn their trust slowly) some people find that removing hiding places by day helps socialise them as they can't hide from you and will hopefully learn that they don't actually need to.
I know it's disappointing when they seem scared of you despite putting in lots of time reassuring them, but hang in there and keep up the good work. Some pigs just take longer than others, but most will respond eventually. Good luck.
