My ancestors were one of those MJ that established Kismayo, they got permission from the sultan of Zanzibar to do it.
The Sultan of Mahra was under Omani hegemony as well lol.
Dhofar war was in the 60s, as you said MJ have been living in Dhofar and eastern Yemen for generations. The fought for the sultan of Oman. Arabized MJ got high positions in the armies of Oman, Yemen and UAE police.
The Boqor had a palace in Zanzibar because he used to travel to zanzibar. The dynasty used to intermarry with them as well, as did the sultans of Oman/Zanzibar.