Gelding does not "cure" anything!!
I have had Stallions all my life and I have NEVER had a stallion that bit.
I have had colts that bit (this is the problem with calling everything "stallions" !!)
Colts are teenagers, young boys, rough housing and pushing the limits all the time.
Colts are or can be a nightmare.
Colts grow up, and, if they are handled correctly, and taught manners, they grow into stallions such as the three I have at the moment, who are better behaved than most horses, geldings or otherwise, that I know.
Colts that are not firmly handled and taught manners, when gelded, will grow up into bad mannered geldings that bite, rear, kick, etc.
Gelding will change NONE of that.
All gelding does is remove the drive to breed mares that are in season.
Some of the nastiest horses I have ever handled have been (bad mannered) geldings.