I think that everyone has given some great advice in this thread. I can't help but say that I'm wondering if Nebo could have caused some of Bon's problems. It sounded like Bon had been fine until Nebo stayed there. Nebo is one of those dogs like Shelteez said that can react poorly to an intact dog, especially dogs that are bigger than him. They got along very well and played until they started trying to mount eachother or food was involved. I don't know if them getting pissy with eachother could have made Bon leary of other dogs.

I really do not think Bon is aggressive he's testing things and seeing what he can get away with right now. Nebo does not like to share water at the park either, he's never got into a fight with a dog over it, just growled at them.

Although I think neutering greatly helps, even with the reaction other dogs will give him it isn't the quick fix. Nebo was socialized a ton plus neutered at 4 months old and he has his moments still. I'm not sure if I would wait fully 2 years but if that is what you think is best for him then you should do it.