In the article, Paypal's letter doesn't say you're not allowed to be an aggregator, just that you're not allowed to be an aggregator that lets merchants get around Paypal's acceptable use rules. Maybe Airbnb has assured Paypal that it does not let merchants circumvent these rules.

Airbnb allows only one kind of "merchant"---the type who wants to offer living space for you.

This product on the other hand lets anyone offer "experiences". To put it lightly, you could have someone offer the "experience of sex" (illegal) or the "experience of touring the porn studios of the San Fernando Valley" (legal but against Paypal AUP).

That's true, but if you look up PayPal's acceptable use policy at https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&c... , you'll see that PayPal prohibits "payment processors to collect payments on behalf of merchants".

So, it's not just because they're worried about what you sell, you're not allowed to process payments on behalf of others at all ... which makes the whole Airbnb-PayPal thing that much more interesting.

By the way, here's a link to an article that does a good job of explaining why acting as an intermediary for other merchants is risky: http://www.braintreepaymentsolutions.com/blog/high-risk-mech...