There are four scenarios, assuming we agree to what "safe" is.
- 1. Visiting paypal using a safe browser
- 2. Visiting paypal using an unsafe browser
- 3. Visiting a pishing site using a safe browser
- 4. Visiting a pishing site using an unsafe browser
The immediate result is only affecting scenario 2, so there will be some loss of business.
In the long run, paypal expects users who hit the scenario 2 to switch to a safe browser. And paypal is big and important enough (whether we like it or not) for a reasonable number of users to do the switch.