There's no conclusion to be made at this point and people shouldn't be making assumptions. Humans don't always do what they're supposed to. A lack of radio communication doesn't necessarily mean the crew was incapacitated. Perhaps they were so busy trying to recover the plane that they simply forgot to make a radio call. Unlikely of course, but everything that happens in regards to plane crashes is unlikely. In every plane crash, something happens that shouldn't have happened, quite often more than one thing.