I don't know that this is selective punishment. It does seem to me that Heymann forgot that his job is supposed to be about justice.
The system in which he works doesn't necessarily remind prosecutors of that as often or as impactfully as it should, and you're right, we need to fix that. There definitely are structural issues here that start with the knee-jerk "tough on crime" mentality of many voters.
That's exactly why we need to make as much noise as we can -- to show the politicians and prosecutors that some of us feel strongly that the system has been over-optimized in the direction of prosecution.