The political strategy in Somalia, which is really going to have to be owned by the Somali government or governments and not by external actors, is to address grievances.
Al Shabaab thrives off of grievances, both real and sometimes exaggerated, on the part of clans and other social groups. There are groups that have lost their land. There are groups that have been preyed on by security forces. There are groups that feel under-represented or excluded from political compacts.
Somalia is first and foremost a political problem, not a military problem. If those groups were brought into dialogue, if they were made reasonably satisfied with the political dispensation in the country, al Shabaab would be denied oxygen. It would have very few tactical partners, and mostly it relies on tactical partners, not groups that are deeply committed to it. That would make the residual military problem much easier to resolve.
As you quoted me, just relying on a military policy to harass and decapitate al Shabaab does weaken the group, but it's never going to solve the problem.