I had a long discussion with my vet on habit behaviors vs hormonal behaviors when I got Powder neutered – the way he explained it is the older rabbits (after a year is when he starts to caution against habit vs hormonal with males) that are neutered can form a habit and neutering will not fix it. We had the issue with Powder and humping, it had become so much a habit for him, neutering didn’t deter him from humping poor Stickers for up to 20 minutes straight and causing her all sorts of stress during their bonding. It is possible to break their habit behaviors, but it takes redirecting them and positive reinforcement training and being very diligent about it. When he starts to spray, move him into the litter box and keep litter boxes near where he does it, clean up any area with something that will remove the scent. And even then, he might still do it sometimes… it’s like teaching a kid to stop chewing on their nails, it’s possible, but it’s hard (I should know, I am 25 and I STILL chew my fingernails lol).