Yes, it is mating behavior. 6 months is not too young for a neuter, unless he weighs very little.

Definitely mating ritual. He loves you so much he wants to make baby bunnies with you. 😉  I agree, you should be able to get him neutered sooner rather than later.

Well, it is better not to have elective surgery during the hottest months, since risk of infection is higher in warmer weather. But a male neuter only leaves 2 very tiny wounds, so you have to weigh the pros and cons.

I’m not sure you risk him becoming aggressive, that’s mostly seen in dogs who are neutered after they’ve established a habit of aggressiveness (as a rule directed towards other male dogs).

Frustration can be a thing though. I had a bun that suddenly became completely sexually obsessed. He was fully adult and long past puberty, so it was late onset, which is not unheard of in rabbits. He didn’t get any rest, the poor sweetheart. I had him neutered and he went back to “normal” after like a week.

I will add that while there is a likelihood it is ‘mating’-related, female rabbits will also circle and hump owner legs, typically in excitement. Regardless, neutering will be very beneficial for these urges. Whenever your rabbit-experienced exotic vet is comfortable doing so is fine, and especially compared to an invasive female spay, a male being neutered is a simple procedure nowadays.