Obviously either way it's pretty implausible, but that's not necessarily a bad thing. Sometimes the best timelines come out things that would seem crazy in our world but are technically possible. In the context of the original post, I will say that it is probably the most likely way to get a monarchist Israel, and I feel like it would be an interesting concept to explore. Of course it may create friction with much of the other Zionist leadership, particularly Republican secularists. You'd likely see a Jewish Ethiopian Solomonic prince working closely with the more religious Zionist faction, and perhaps his rule would be a compromise with the secular Zionists like the Rabbinate was OTL. Of course, a bunch of things would have to go exactly right in order for it to work out. You'd have to see the Ethiopian prince not only convert to Judaism, but then have a long story arch about him rising through the ranks and leading Israel to to victory, perhaps establishing his own powerful organization to rival Haganah. Likely he would be seen as a Messianic figure by his followers (which is not necessarily unheard of, given the history of Messianic movements in Judaism throughout history as well as the fact that Rastafarians see Selassie as a messianic figure). He may even have to make radical promises, such as agreeing to restore the temple, which would create extra friction with Arabs or more tension within the Jewish community (the latter of which would especially be so with the religious Zionists if he had to back out on the promise after independence, which would likely happen). So it's implausible, but it's technically possible, and it would make a killer story with perhaps one of the most interesting protagonists of an alternate history timeline I've seen on this site.