Was about to post the same link as puddock... :)
My team work with the placebo effect a lot. It's fascinating.
Far from, there seem to be numerous interesting properties of honey. Certain types are used successfully in wound care, for example. In the lab it has anti inflammatory and antibacterial properties, but it's still not clear how that translates into real life clinical use.
The hay fever thing bones from the fact that you can desensitise to pollen allergies by ingesting pollens orally. However... Most get broken down in the digestive tract before being exposed to the immune system, and The types of flowers that make up the pollen in honey aren't exactly the same as the types that cause most people's hay fever. Grass pollen is wind borne, for example, not bee transferred.
But overall, op, I'd say let him eat it. It seems to be a bad hay fever season this year, my poor dh is suffering terribly and his antihistamines aren't touching it :(
I love honey, I've eaten it every day since being weaned :) (yes I know, botulism/shouldn't give it to babies...this was the seventies...)