Airlines can't take payment in bitcoins. They can set the price in dollars or euros, but to take payment they owe only the national currency of the country in which they sell a ticket. This is a mandatory condition of licensing. To take bitcoin can only be a mediator, but I didn't trust them.
This. It is somewhat simpler to use such service, but it makes much more sense to exchange BTC yourself at a better rate and pay in local currency, there is no way such companies can offer a better rate then specialized exchanges.