Basically as the title. Was the SA purged because Hitler feared Ernst Rohm was a rival or was it because of his sexuality or was it a combination of both? Or was it more to do with reducing the power of the SA?
Fear that the SA may have become too powerful / rebellious towards the NSDAP.
Hitler was always paranoid about losing his power over the party and felt that the leaders of the SA were his biggest threat at the time.* They had just as much support as the party with a larger proportion engaging in violence.
The SA could have forced a change in leadership, much like an inner party political coup.