I am against using a fixed price. If an account owner is willing to pay $50, and a hacker wants $50 to give the account back, I don't see an issue with facilitating that if you are okay with facilitating a transfer for $25, or some other arbitrary number.

I would also obtain a separate signed message from the purported account owner to make sure someone is not effectively buying a stolen account. You should also solicit the opinion of theymos or another admin for each transfer prior to facilitating the transaction in order to give them an opportunity to voice concerns about giving the account back to the claimed owner.

If you are going to say your service is "no questions asked" and subsequently txid and/or address details, you will lose credibility with any hackers who want to use your service. Ditto if you later use that information for some kind of investigation. Also, you should keep in mind that a hacker may tell you to send the bounty to an innocent 3rd party's address in an effort to frame them as a hacker.

If implemented, the correct sub for this would be services, not meta.

I am on the fence if this is something I would offer myself, probably not. Although perhaps it would put pressure on the admins to put more effort into account recoveries.