When? The officer corps is made up of career officers who openly choose to stay in the military for life. People from poor regions and the Druze are more likely to do so. The top military echelon come from all sects and all regions.

The problem with sectarian people is that just because the Army didn't side with them, they assume its because of Alawites. Syria isn't at all like Libya, Yemen or Egypt. In Libya the army units from areas that rebelled defected.

Entire areas of Libya disappeared from state control in a week. That never happened in Syria. Parts of rural Homs, Idlib, Northern Aleppo, Daara countryside and Deir ez-Zor were gone easily and their men defected en masse. The rest didn't, the rebels took control.

In Egypt the regime was the military. It wasn't Mubarak. He was the leader and they followed him but the military was pervasive throughout society ever since Nasser's days. Mubarak was widely hated before the revolution. The military was clearly not on the side of the protestors in the beginning but "joined" them when it was obvious Mubarak would go. That wasn't the case in Syria. Assad was popular before the revolution. He ruled a state with ideological party and its legitimacy was that. Unlike Sadat Hafez and Bashar never abandonded their ideology.

In Yemen parts of the army stayed loyal while the pro-Islah units defected. Saleh had rivals for power like Ali Mohsen his cousin. That guy was actually part of the reason why Islah was formed, it was his baby. Syria at best had Mustafa Tlass. A corrupt old man who many did not support. He didn't have much influence and nor did his son. The civilian side of the Syrian government/military was firmly in charge. The SAA serves it doesn't dictat.

Alawites however have been disproptionetly choosen for the security services, I'll give you that. This one is actually true. The government never trusted them and it setup rival security branches to check up on other other.