Imagine

Someone codes some utility, but not copyrights it or adds any license. Some company steals the code releases it as commercial closed source executable and then sues the original author for copyright infringement. Is this possible?

I wouldn't think so. Besides being a stupid thing to do, there wouldn't be any point in a public domain if people couldn't contribute their  works to the public domain if there was a chance that could happen. An analogy would be the Disney company litigating against the estate of Grimm for their stories.