OTOH, there's the huge confounding factor that it was shortly after I came back from Ireland to Italy, and Italians are harder to creep out than Anglo-Saxon people. Stand one metre from (say) an American and they will freak the hell out; stand one metre from an Italian and they'll wonder whether they smell.

The example you give illustrates the difference in personal space norms between cultures, I'll take it on your word that Italians also happen to be less easily creeped out. But the difference in personal space norms doesn't itself indicate much about who is most easily creeped out. Trying to make a social approach and standing a more than appropriate distance away could itself be creepy (although obviously not as creepy as a personal space invasion itself.)