If the snowstorm is bad enough, every travel method will be disrupted. Driving would certainly be just as delayed, or more, along with a high risk of getting into a crash. Biking would barely work at all. Walking could work if you have the right gear, but you need to be prepared and take it slow. Flights would be delayed or cancelled. Busses might be ok, if there are bus lanes for enough of the route and the plows got to them, but even that's iffy. There just isn't a good way to travel when the snow is that bad, and holding the commuter rail to an unrealistic standard doesn't really help.