The biggest supporters of Somaliweyn were always Darod. This is not even something that can be argued. Darod simply had the most to gain from Somaliweyn. The unification in 1960 lowered the political power of Isaaq and Hawiye while increasing that of Darod. This is why, from the beginning, in 1964 PM Abdirashid Ali Sharmarke went to war against Ethiopia. And also why Harti traders started the Shifta war in 1963. Egal basically signed an MOU recognizing the validity of the southern border with kenya. What did MSB do when he came to power? he immediately declared the MOU signed by Egal invalid and launched a war against Ethiopia in 1977.
Somalilanders of course cared about Hawd, and were pro Somaliweyn because of this, but it is not accurate to say they were the biggest supporters of it. Darod were and probably still are do to what is at stake for us. Hawiye, Dir, Isaaq, and D&M all have the vast majority of their people within the borders of Somalia, no more than 40% of all Darod live in Somalia.