A Quick Bird Question

I have a quick question/bleg and I'd appreciate if anyone can give me their thoughts. Right now here in southern Wisconsin, it is snowing somewhat hard. We've got a couple inches on the ground and we'll be getting a couple more inches before this storm turns into an ice storm. About an hour ago a cardinal flew into my back yard and started eating in my bird feeder. He hasn't left. I'm guessing that it is just sheltered enough from the storm to make it warm while he's in there. Should I allow him to shelter there for as long as he likes, or should I shoo him off so he gets back to his nest before the precipitation turns to freezing rain?