You are grossly underrating the ottomans naval capacity. They inherited the naval fleet of the mamluks who had reverse engineered and modified spanish carracks used to expel the portugese from chaul in 1508. The ottomans had all of this at their disposal and failed to expand beyond the medeterranian after their coup in egypt and muslims suffered as a result through the red sea to the indian ocean. Besides that, there were ottoman fleets present in al shihr the same year berbera was burnt

suleiman al khadim was more than capable of sending support to adal but failed to, the same way he failed to support the muslims on the swahili coast, in india, and most of hadhramaut. as a matter of fact, sulaiman himself sacked and looted aden and hung its emir

. they had no vested interest in defending muslims only exploiting them