Answer: monarchy was still the most common form of government at that time (2nd half of the 19th century), i.e. republicanism was not very popular and frequently viewed as destructive. Don´t forget that in Italy itself republican regime was established only in 1946 (after the referendum): majority for republic was a narrow majority. So-called 1st republic lasted from 1946 to 1993.
Explanation: Garibaldi was not a republican politician and Savoy dynasty (even though it was not of Italian origin: today Savoy makes part of France, in Savoy French was always spoken, temple of Savoy dynasty is in Chambéry which is in France) was probably the most suitable.
