Now, this doesn't necessarily mean Safari is a bad option, not even an insecure browser, but in the eyes of PayPal it is lacking two important anti-phishing security features that "Internet Explorer 7 or 8 when it comes out, Firefox 2 or Firefox 3, and indeed Opera" already pack in. The two features mentioned by Michael Barrett, PayPal's chief information security officer, are a built-in phishing filter and an anti-phishing technology, called Extended Validation certificates.
PayPal happens to be in a very unique position for making an educated assessment regarding web security, but we don't see either of those two technologies making miracles for saving users from fraudsters. That said, we wouldn't be surprised if Apple implemented them on its browser in a matter of weeks or months, depending on how badly they are demanded by its users. At the end of the day, there is no better anti-phishing filter than yourself, being aware that scammers are out there and they are trying to get you. Just make sure you browse the right sites and follow links where you can trust them.