Please be aware that melaleuca (tea tree oil) has been known in rare cases to cause breast enlargement in young boys and is suspected as an endocrine disruptor in girls, too. A strong concentration is a skin irritant, and I would be very cautious about using it where he might rub it into his eyes. Until further research proves it's a limited problem, I'd avoid using it except in very limited circumstances where children won't be exposed to it. It is a powerful cleaner and has strong antibiotic action, but other products do, too.
Very light applications of neosporin or any healing salve will probably be sufficient. If he scratches at it, there could be some itching, either from the dry scab pulling at surrounding skin during healing, or from the wound itself. A touch of cortizone cream should help with that.
Don't worry too much about scarring. Kids have an amazing ability to heal with little or no scarring. And if he does end up with a bit of a mark across his nose, it will probably be kind of cool, since he's a boy.
I see liquid bandage suggested. Probably another thing to avoid near his eyes. The two different types I've tried have stung like mad on an open wound.