No.
In my experience, prosecutions are rarely politically driven. Further, the mechanism that our criminal justice system provides in close situations (e.g. Zimmerman) is a trial before a person's peers with a very high burden of proof. Using the Zimmerman case as an example, I analyzed (and posted on here) that I believed he had a strong defense. However, that thought is not mutually exclusive to the thought that I also believed the state had more than probable cause to bring the charge and it was not unethical to prosecutor.
Similarly, here with Rittenhouse we have the very public shootings (with significant portions caught on video) of multiple people and two ended up dead. It would have likely been unethical of the state not to at least bring the facts before a grand jury to determine whether probable cause existed to charge. Further, it would then likely be unethical to dismiss the obtained indictment and its corresponding counts.