There are more scholary articles painting a far more nuanced picture, compared to a LinkedIn post done by a mercenary.
Nowadays, their backbone is found between the riverine valleys, among foreign volunteers, marginalized groups, and general young people.
I think the problem is that the current Al-Shabaab is not a product of a specific clan but an actor, just like the FGS and FMS that utilize clan affiliations to further their own goals.
Almost half of Al-Shabaab's forces are made up of people younger than 19. Not only that, they disproportionately come from motherless or fatherless homes. Interestingly, no specific tribe is mentioned when joining, but factors such as economic crisis, hatred of foreign forces, and a perception that Islam is under threat in Somalia and the wider world.
To get back to your main point, with the exit of Aweys in 2013 and the consolidation of Al-Shabaab from a Taliban-style Islamic-law-within-our-country to international jihad, tribal political forces waned, replaced by young extremists with globalist views. Tribe, like everywhere in Somalia still plays a role, seizing on tribal infighting to recruit auxillary forces to take over towns.