When I add a post notice to a flagged post in the review queue, the flagged posts stays in the queue. It shouldn't, because putting the notice was obviously the flag handling action then. Keeping it in the queue just increases the likelihood that another mod will double handle it prematurely.
The question was flagged as Not An Answer three times. And rightfully so given our standards. I could simply delete it (which is the common practise) or put the post notice and give the OP a chance to improve it. Both actions are handling the flags but only deleting would mark the flags as handled. I can obviously mark the flags as helpful after putting the notice (and I did in this case) but I shouldn't need to. Also, when I mark the flags as helpful, it needs another flag to bring it back to our attention. Ideally, the post could automatically pop back to the queue after a week. If the post wasn't improved by then, we can still delete it to maintain our quality standards.