I've seen this before, but you also have to remember that Izuku was also trapped in that same villain earlier that day and only All Might knew. Another thing to remember is that he was s*icide baited earlier that day and then left on a roof by All Might after his dreams were crushed. I think hearing Bakugous explosions somehow told him that Bakugou was in trouble. I think that if it hadn't been for this, Izuku might not have made it past this point. So the public knows that Izuku saved Bakugou, but personally I think Bakugou saved Izuku too.