It is possible and I have experienced the same. Though not from bounty, I got the airdrop of worth almost 0.2 eth in Ionchain token. Next they emptied out there wallet, sold everything and ran away with all the investors money. Its really sad.
You contacted developer, and you asked smart contract, I think have been in trading at fork or etherdelta then maybe there is no fraud. Try contacting them through their telegram channels.