what did Italy do in the first few days of June, 1940?

My father had a ticket on an Italian boat (the "Augustus" - Italia line) departing Lisbon for New York on June 4, 1940. He apparently left Switzerland for Lisbon in the first few days of June. He said that the boat was then unable to take passengers to the U.S. because Italy came into the war just at that time. But everything I've found says Italy came into the war on June 10. So why wouldn't my dad have been able to get on that boat on June 4? Any ideas?

Leo's Ticket on the Italia Line - Leonid Hurwicz

 

The Italians could anticipate that ships at sea would be captured or sunk by the British upon the outbreak of war; well-known liners running scheduled routes would be particularly vulnerable. They might also be subject to internment if they did make it to American ports.

Large fast ships like Augustus were important assets. During the war they started converting her to an aircraft carrier, to be named Sparviero, but this was never completed.

If Augustus was in Lisbon in early June, I expect she would be ordered home while she could still pass through the straits of Gibraltar. For that matter, with hostilities imminent, she may not even have gone to Lisbon; that would explain why Leo's ticket was cancelled.