It seem to me a major problem are also that the Omani was slave traders, I think they need to diversify hard away from the slave trade in the 18th century, they don't need to stop, but if it stay treir biggest trade, they won't be able to survive it being stopped. Maybe if they move toward their African possessions become producers of cash crops, it could enable them to integrate into a European powers trade network.
I doubt there is enough land to do large scale cash crops. Further, why would desert nomads/merchants decide upon an intense cash crop model? It seems quite arbitrary.
If anything, the only trade that can trump slaves in east Africa for them, would be ivory. Which is not as reliable as slavery.