Before the civil war, there was an Italian community concentrated in the Benadir region, comprising up to about 10,000 people. I doubt even a handful of individuals will return. Those Italians of Somali descent who might consider it are likely too old, and their descendants would never willingly choose to live in Somalia.
This seems like mere PR, an empty promise that he knows he doesn't have to fulfill. It's a gesture to maintain good relations with Italy and, by extension, the EU. By doing so, he aims to present Somalia as a country that respects the rule of law and as a safe investment option. This portrayal suggests that the government protects the property rights of even non-nationals.
HSM foreign policy is pathetic but atleast it works, from removing the arms embargo to debt relief to cobbling up the big players in the world to disavow the MoU, it works. HSM knows just how bad Somalias international 'capital' is and works with what he has.
Rows of president fail where in HSM succeed. He gives of that aura of a weak men, and he uses that in his advantage. Sheikh Sharif with his history in the ICU and Farmaajo with his nationalist rhetoric makes the international stakeholders nervous, but a man like HSM, they believe is weak and therefor trustworthy. In their minds under him, Somalia is a obedient western adjacent country at the crossroads of world trade, and therefor more willing to give him what he wants as a show of good will and trust.