I assume Tetsuo naitoensis is that strong only because it ate every person in the Nagoya city. In fact it began its career by eating people, so it quickly grew stronger.
I'd say Tas's super power would grow significantly stronger if he had collected those pieces of the Tetsuo naitoensis clone and eaten them. It would have been disgusting to eat them raw, but he could have cooked and seasoned them properly. That being said, he plans to never fight again, so it's not like he would need combat power.