This happens with selenium toner all the time and I've never seen a reduction in toning. Granted it isn't a straight developer but its a similar concept. I think even if whatever organic substance got into the development tank itself it wouldn't do anything negative. You're basically dealing with metallic salts throughout the entire process, not biology.
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.