I'm not going to discuss it in the ad, and exacerbate the problem.
You seem to be under the misconception that we freely ban people that we suspect are scammers. We don't. It is not our place to act as judge and jury. Spammers - they're gone. People confirmed to have used false information when registering - gone. Otherwise, there is a process, and it takes time.
As far as comments in the ad - posting basic warning is fine...if you're sure. It's best if you include proof (ie identify the origins of the pictures used, show that the email address is all over the 'net, etc). Once that is done, a BOI thread should be posted...and any subsequent commentary belongs there. The mentality that it's okay to pile on in these ads tends to spill over into other ads; so, no, it is not acceptable. Disruptive posting is disruptive posting, and is subject to infractions.
As far as why that person is still able to post - I was attempting to tie it to some other ads, and hadn't had time for an in depth investigation. Please refer back to the earlier explanation about process and time - a PM sent (with read receipt) has not been opened, so the clock can't start ticking. That account will likely never make another post, anyway.