Perhaps I misread your particular suggestion before. In this particular case I'd know who is posting the thread anyway so in such a case couldn't I more easily just post it for them? The only difference would be whether or not they'd be able to respond anonymously to the responses received by the thread. I'm not totally closed to the suggestion in the format you've made it in and it could potentially be done this way on a case by case basis. If this was a very infrequent thing (with a time limit for responses so I can revoke access to the account) then it could be manageable - but if it came to that time and they still had not received any responses then that would not be ideal. If I was getting such requests very often it would probably be too much to manage honestly so I'd grant this only in a case I thought was warranted. Obviously my judgement alone is subjective but due to the private nature of such a request there is not much of an alternative.
Another thing to consider is if someone uses such an account to post something anonymously that is revealing concerning (and potentially time sensitive) information that puts me under a duty of care being the only person who knows which user it is where I may not even be able to see it or respond quickly enough in a dangerous situation. This is a situation I would obviously much rather avoid.
