I think the key to make a openbazaar airdrop work, would be to have official bitshares notaries (multisig 3rd party for escrow and arbitration) provided by the bitshares network, who ensure bitUSD can always be used in escrow, and who oversee the referral program and ensure it is not being gamed. These notaries would be delegates who campaign to get this extra job, and would also be the delegates that are responsible for creating the inflation blocks that fund the referral program.