Then sign and send the audit log in realtime to the authority which A provided their logs to. Same effect no blockchain.

You could also encrypt and publish it. But realistically there is always going to be some entity actually responsible for enacting the consequences for non-compliance and they are the only entity that really ever needs to check these logs.

I am not sure I understand what the incentives to “mine” this blockchain would be. Without a certain block difficulty, which requires many miners, it will be trivial to rewrite the entire chain.