Actually, the Greater Somalia was concept for a very long time. Somalis are divided into four (formerly five) countries and they always tried to make it into one. In present day concept which forces boundaries to be fixed and nonnegotiable, that is taboo.
What is unacceptable. that Omar is talking about US being some kind of slave of Somalia?
Rhoda J. Elmi, the deputy minister of foreign affairs for the Republic of Somaliland—a small breakaway state on the horn of Africa that is not recognized by any foreign nation—tweeted a video of the speech with English subtitles that landed Omar, who had addressed the largely Somali American crowd in her native language, in hot water with critics.