He clearly mentioned he wants to work for BTC , there are about 1000 freelancing sites with 100000 projects paying in dollars .He wants to earn btc that's why he's here in the first place.
And, appropriately enough, it seems payments in that site are exclusively made in BTC - hence the XBT in XBTFreelancer. However, they have made the questionable (although understandable) decision to show the amounts involved in USD.
As the site puts it:
Employers pay for projects in bitcoin
Freelancers get paid in bitcoin
* 100% bitcoin site. Build-in escrow service. Amounts stated in USD for clarity purposes only.