If using Paypal imposes additional operational risk, it's entirely reasonable to charge users extra for using Paypal. Offer them lower prices for using a payment method that isn't 100% shite.
As a seller, you are going against paypal TOS if you charge a fee to use it, the same way a credit card carries the risk of chargebacks but you aren't alowed to charge a credit card fee. I agree that this would be an effective risk-management tactic (less the fact that the fee you charge to mitigate the risk still gets processed by the risk factor) but it would also worsen your chances of getting banned.
This is indeed what I would do if I'd absolutely have to use PayPal. Customers can use it if they really want to, but they're the ones paying for the risk.
