I think the term Jareer is stupid. It refers to just one of the many physical attributes of the Bantu. The term Bantu is more applicable as it is a neutral term and emphasizes the foreignness of these groups more.
Yes, they refer to themselves as Somali Bantu; however, to say that they are foreigners is bogus and has no basis. As a matter fact, some of the Somali Bantu who settle around the Lower Shabelle river, particularly, reer Shabelle and Makane have been reported to be one of the indigenous people in the Horn of Africa. I think you're referring to the Gosha people who trace their roots to Tanzania, Mozambique, and Malawi. These people were taken to Somalia during the slave trade by Arab slave traders, and they run away from that ordeal. Today, they are Somalis, speak Swahili dialect and Somali as well.