The new capital should be in Mudug imo... for a couple of reasons.
1. Al Shabaab control the vast majority of the south
2. Mudug is flat lands and not mountainous which is fairly easy to control.
3. The communities who caused mayhem in the shabelles will return to their original homelands, meaning that those regions will be less oppressed and less likely to fuel Shaabab recruitment.
The returning communities should be settled in the surrounding towns of the city but not be allowed in the actual city.
Once there is a legitimate government it should purchase the land from the clan that resides in the area as they will lay claim it, and strictly control the population. The city shouldn’t have any IDP camps, the city should also maintain a population of around 50k-100k.
Just my two cents