They are a private company, they can do whatever they want. Also, I am a fucking idiot who should be deprived of clothing, food, heat, running water and telephony on account of these things being provided by private companies that can do whatever they want. Just thought I should insert that here, so no one else has to in case the thread takes off in that direction.
In all seriousness, it should be said that PayPal is yet another online product/solution approaching a near-monopoly, getting away with awful behavior simply because there are no decent alternatives.