Evans head does not require radio, the display line is set 210 meters from the crowd line and runs north south. The marshals are relied on to scan the skies for such an incursion. The CASA was there and spoke to pilot of said drifter, he's still flying!! I have more safety concerns with string departures mixing it with various performance air craft and intersection departures,,, there was another incident with the mustang joining mid x wind an finds an out bound air craft departing mid field straight at him. I find those moments more concerning and a radio would not have fixed the near dissarster over the crowd.