They had radio, they had TCAS, they had ADSB-in that announced traffic in their headsets (although some functions were inhibited as they were too close to the ground). They basically had everything available - the next step is controlled airspace. What more do you suggest? The comment was that they received too many traffic notifications with the equipment that they had.
I am very skeptical about the radio not working. They go to a lot of trouble to show that the faults in the antenna were pre-existing, and not a result of the crash. But that means it must have been a problem a long time before the crash. How long can you operate in that environment without someone noticing that your radio isn't transmitting? More likely the radio call was over-transmitted, or just so routine that people couldn't specifically remember it.