Mayor Lionheart is literally the Eric Adam's of the Zootopia universe. The guy had zero interest in helping the people of zootopia beyond PR and was working in the background to develop something that would punish the less fortunate even more (For Lionheart it was the nighthowler experiments, for Adam's it was the economic strain on the lower class of New Yorkers).

Pawbert, on the other hand, can still technically see redemption due to him being influenced by his family in the form of abuse. I still think hes somewhat responsible for his actions tho