Why would Italy keep its fleet at Taranto?

Why would Italy keep its fleet at Taranto if Britain had more carriers in the Mediterranean?

Italy believed the harbour was too shallow for a torpedo attack and expected air-force warning of any British approach.

The Italians historically believed Taranto's shallow water protected the fleet from torpedo attack. They also expected the Regia Aeronautica to warn the navy if British carriers approached. That confidence resembles the assumptions behind Pearl Harbor, where another fleet believed its anchorage could not be attacked. Extra British carriers therefore would not automatically make Italy disperse before the raid.