As I said has he come close to lightspeed before that? No he hasn't. He has gotten stronger, but in that instance that was shown in Mighty Avengers it didn't say radio waves was his max speed, but that he was outrunning radiowaves. So even if the writer did mean sound waves he could still be running 5x the speed of sound, but that's still drastically different then lightspeed. Technically that would mean he is FASTER then the speed of light too as he was outrunning the waves
Show me some examples then Mindset prove me wrong. As what he has done and what he is stated to do completly contradicts that statement in Mighty Avengers.