Agreed; it's an old rule that if the guy is repeatedly fouling you, intentionally or not, you throw a little back his way.
I thought Agbeko showed incredible professionalism and restraint given he had a dirty fighter in front of him and a screw-up ref beside him. He might just be a good guy who won't stoop to cheating even if the opponent will, or perhaps he felt the deck was so stacked against him he couldn't risk giving the ref an excuse to deduct more points or disqualify him.
At one point there was an accidental collision of heads due to both fighters leaning in -- the ref chastised Agbeko. I thought that said everything, and Agbeko probably did, too.