Stupidity: The type of steak that Clyde demands has a sharp kind of bone inside that can easily be used as a weapon. No prison would be foolish enough to overlook this fact, especially as the warden had everything double-checked.
Stupidity: Despite the fact that Clyde is somehow very easily managing to kill people from his cell, it never occurs to assign some kind of security or a camera where he could be consistently watched in case he did something out of the ordinary. Nor did they even both to thoroughly scan his cell, something which should have been done in the first place for any irregularities, and especially once again after it became known that he may have been still killing people despite being locked up.
Stupidity: The first time they go into Butler's garage next to the prison they are breaking in, but Butler never witnessed any break in clues to raise his suspicion. They replaced the lock with the exact same lock. It is clear that they didn't know that this was his access point to the prison, but once they found out there is no way to cover up that someone compromised the facility. How is Gerald sure that the bomb will remain under the meeting room while on his way back to the cell? He has a camera in the meeting room but in the bomb room he didn't bother to put one.
Answer: Because Nick knows this man is guilty. He says it to almost imply, "well since I'm getting off, may as well make a visit to your family next. You married, Nick?"