I got the same response from my attorney for my AP to be approved. It is very funny that first he said I can not leave the country while AP pending and they he said that I could leave once my biometrix appointment is over. I am holding it until the critical situation comes for my desparate need to go to my homecountry India.
Usually it takes 90 days to get AP nowadays. I checked in , some have received it in 20 to 60 days. If you do not plan to return for a long time, you will not be able to use it anyway when you return (you may have to go to the US consulate before coming there to get letter / keep extending while you are out there).
What you can do is...
1. Call the number in your AP receipt document and look for an opportunity to expedite it. If this is very critical, they can guide you on how you can expedite it.
2. If possible, get an InfoPass appointment to your local USCIS office and go there in person, try to explain the situation and make them feel on what you are missing.
3. Visit the senator's office in person and talk to the Senator and explain the situation and request to expedite it. Before you make your personal visit, explain the situation to the exec assistant of Senator and get her view on what would be Senator's response.