Business wise they will choose the currency who has the widest reach and already can be exchanged to FIAT. In most countries, BTC is already convertible to FIAT unlike XRP. There are so called BTC ATMs as well that goes to show how wide BTC reach is. There are more companies accepting BTC as well than XRP. So these goes in favor to BTC so why would they choose XRP over BTC.
That's actually the main reason why they chose btc, the scope of coverage of btc. A lot of local exchanges or remittances are already accepting btc, so why use the popular among cryptocurrencies? XRP may have the advantage of cheap tx fee but the popularity of usage is not comparable with btc at the moment. But I feel that later on, PayPal will also add XRP.