With respect to Penny, I think the question is: What punishments, consequences, or lack thereof will best foster public safety?

And a big part of that question is this: Do we think Penny himself poses a threat to the public? Note that by "public", we must mean everyone: black, white, rich, poor, homeless, neurodivergent, etc.

If a certain amount of punishment [of Penny] would improve public safety, then we should do it.

But if punishment would weaken public safety (e.g. by discouraging self-defence, or by the threat of wrongful punishment by one's government itself being a threat to everyone), then we probably shouldn't do it.