It is true that two carriers can produce Affecteds, Carriers, and Clears. So even if your dog's parents are both Carriers he may not be Affected. His fanconi status though is only one small part of the picture though and not reason enough to keep him intact.
The reason neuter him is that aggression is often aggravated by testerone so if he showing aggression and fighting with other dogs that is likely to escalate without you intervening. Neutering will lower the hormones and help but he also sounds like he is in dire need training. Also, breeders have worked really hard to improve temperament in this breed. There is no reason to breed a dog that is exhibiting temperament issues.