Toichiro Suzuki supposedly is the second or first most powerful esper, depending on the source and interpretation. How did regular humans do for being able to retain him for incarcelation, if he at any moment can use his wide range of psychic powers to escape?
What do you mean regular humans? The dialog between him and the person taking him away at the end of Season 2 Episode 12, as well as the non-standard binding on his hands strongly suggests that he's being taken in by an organisation that has their own supply of espers.
Additionally, at this point he has had his change of heart - he is turning himself in and going peacefully. So while it's still possible that he's strong enough to break free, he's choosing not to.