This isn’t true. Bosaso’s airport was literally built by the Chinese a couple of years ago. They’ve also invested in other sectors too in recent years. It might not be as much as other African countries but they still have a presence
The Chinese have also had a presence and invested in Somalia pre civil war. They built the pre civil war theatre and stadium in Mogadishu. They also built the north-south Mogadishu Hargeisa highway in the 70s.
It would be naive to think that the worlds largest economy isn’t investing in the closest African country in terms of distance