“He did not show any fruit of repentance.”
Thief was being executed for his crimes.
Thief humbled himself and admitted he was a sinner and deserved to die (Not many on death row do and if they do, would brag about their crimes).
Thief had a contrite heart and no doubt was sorry for all the harm his actions caused others.
Plenty of “fruit” there, especially the first point, the others, Christ sees.