I think his apology was sincere, he has to be around prosecutors who don't want to help the people, who are corrupt and accept brives. Maybe he feels like he is lifting the responsability for all the prosecutors in Korea who aren't faithful.
It seems his plan is to cut the powerful conections of Jo Tae Sup by undermining the people itself, and then placing honest people to take charge, that way Jo Tae Sup will be seriously cipled in the times when he is being atacked.
This feels pretty unrealistic most of the time, but I don't know if I came here looking for realism. I'll flow with the fantasy for now, usually when a manga betrays itself and it becomes just an expresion from the desires/fears/regrets of the author is when I drop off (or put it on hold until...
He has been punched a lot of times, at least I don't feel him as OP anymore, but now they have to do a good character arc for him or at least a good story arc, else it'll feel void.