Maybe the question or the premise are a little confusing. If icing conditions exist, a cyclist has to decide whether to take the risk of riding when other safer forms of transport are available, or else mitigate this risk by using the proper equipment. Weather prediction is a science but it’s not exact, and weather is only one factor of many that determine surface conditions. The NWS or Bike Forums members can’t make the decision to ride for anybody. Doesn’t it seem unfair to ask?
Presuming that bike commuters have a bike and a home and some sort of neighborhood or trail nearby, go and try out various slick conditions a little at a time until you feel comfortable enough to commit to a commute. I mean, if you have a car or another way to get to work already, it’s hard for me to understand the benefit of the risk of riding to work in uncertain weather and surface conditions you’re not sure about the ability of yourself and/or your equipment to handle. Like, what is to be gained? What am I missing? Is bike commuting a form of thrill seeking for some people? It seems like a ridiculous question but I have to ask.