Or, to provide a unifying national symbol whose interests are innately aligned with that of the state.
You keep saying this but you aren't responding to my counterpoints.
How is the monarchy going to unify the country if it is practically exclusive to the Amhara people and the Ethiopian Orthodox church? As I said earlier, Ethiopian Orthodox membership is rapidly declining and the Amhara people barely make up a quarter of the country's population. I don't understand how a monarchy so tied to these aspects of Ethiopian society would unify the country.
If the Amhara population and culture were say, as significant as that of the Han in China, then I would completely agree with you. In that scenario the reestablishment of the monarchy would be a very viable option.
whose interests are innately aligned with that of the state.
The interests of a monarch are not necessarily aligned with that of the state. They should be, but this is not always the case. Any politician should innately have their nation's interests at heart, just as any monarch should. The problem with the monarchy in Ethiopia, which is a problem common to monarchies in developing nations, was that it became a separate entity from the country. For much of his reign, Selassie was simply looking after the monarchy, not the country.