Good take, only thing I would add is I don't think the US is interested in a state building/unified Somalia in the sense that all states agree with eachother and work together. Status Quo is the unity they want, where its Unity in name only but otherwise there's political stagnation and constant fights. This way Central Government can be influenced by using different states as a counterbalance, ie no debt relief unless such and such state sign off on it or Election Law passed in Parliament means nothing unless states sign off on it in Dusamareeb convention, etc.
The drawbacks of the method you described are unpredictability and long-term unsustainability. Manipulation has limits. Just look at Ethiopia's baby project called the Biixi regime. Once it saw an opportunity with the Egyptian base, it quickly started using it in disregard to the interests of its master, Ethiopia.
If we up a notch, the US has itself encountered this dilemma in the Gulf when the Trump administration has failed to create unified front against Iran. Despite having a large military base in Qatar, the US couldn't completely align this country with its own objectives. If all these Gulf Bedouin tribes were in one country, Saudi Arabia, it would have been a different story for the US.
I do agree the US is playing a manipulation game in Somalia at the moment. I am just glad Yamamoto is at least in line with the idea of one Somalia.
