Do you do any ground work with him right now?
From what you've described, his behavior is not aggressive. To me, it just sounds like he thinks people are useless and not worth communicating to. I know a couple horses with this "horseonality" and the challenge with them is to get them interested in you enough to where they feel like we are worthy of communication. So you need to have a BIG imagination with these kinds of horses!
To get things going naturally, since you said you are want to do NH with him, I would do 30 minutes of quiet time with him in his stall or paddock for 7 days. Enter the stall and act as if he isn't there. Go sit down, either on the floor, in a chair, on a bucket, whatever, and just wait. Here are the rules:
*Don't make a lot of eye contact.
*Don't try to get him to come over yo you.
*If he comes over, do not reach out and touch him. Allow him to be the first one to touch you, if he wants to. This is important because usually horses are not allowed to be curious about people. We always do things to them and they never really get a chance to just come investigate us.
*When you observe his behavior, do it in a soft way, not like you are concentrating really hard on him lol.
*If at any time you feel unsafe, go out of the stall/paddock and sit on the outside.
*No talking. It's just you and your horse in your own world, just the two of you.
If he doesn't come to you at all during this time, try not to take it personally. That just shows you that he isn't really interested in having a relationship with you YET. But if you do this for the 7 days you will be surprised how interested he becomes. When the 30 minutes is up, simply leave the stall without touching him or looking at him. This will also spark his curiosity of you, and curiosity leads to him asking you questions! This is big for this type of "horseonality" because they generally don't care about people, let alone communicating with us.