Perhaps we could treat the aur-requests more like a bug tracker ?
a possible flow :
request is filed and gets unassigned status
TUs review unassigned requests
If they feel they are right person to handle it, they assign it to themselves. request status changes to assigned, and the TU is now responsible for handling the request.
If they are not, they leave the request unassigned, maybe post something why they are not qualified.
Once a request has assigned status, policy rules for such a type of request are added to the request. Only the assigned TU can accept or deny a request.