If someone has been convicted of violent crimes and the matter is generally known it would seem that he is muchzak barabbim as a rasha. The store owner’s problems with this mafia are also well known.
That being the case, it would have been bettr to write something along the lines of “crime does not pay” or “be warned” and some hope that he does teshuva. Just as Hashem does not desire to punish a rasha and takes no pleasure when He must do so neither should we.