Only just seen this thread. When you find someone on Ancestry with a connection to you (maybe DNA or maybe through their tree) and they won't reply it is very frustrating! I've had it dozens of times. They have either lost interest and dropped out or maybe ill or passed on. Who knows? Still, try contacting them again after a month or so just to see if they have overlooked the first message. Wave a carrot, by suggesting you have family information and photos which you are sure they would find interesting. It sometimes works.
1st or 2nd cousin is a very close connection so keep these people in mind. They are very important. What a shame they haven't replied and don't have a tree. It's possible they just had their DNA done for fun and haven't actually done any research, although I'm not sure what the point is if you're not going to find relatives. Also, you don't mention this, but if you are researching an illegitimate line then these people may not be very happy to hear about you. Tread carefully.
You can definitely add your DNA to various other sites including Gedcom, which may yield success. In addition I would use Ancestry to research the family and build a tree, and this might help identify the airman. There is so much online now especially for the USA. Other sites as well of course, especially FreeBMD.