A smart audit contract can only be sent by the developer?
No anyone, but it would be fair if the developer send the request and publish hers/his audit badge.
Why do you think that a scam-developer should conduct an audit? To him then no one will give money!))) If the sense of Callisto is to focus on fighting against scams, then it will be very good!
Right, however, if you ask the developer for an audit and the developer rejects it, you should go away from that project.