Are NY State employers required to pay workers compensation ins. if they have no employees except themselves?

A sole proprietor did not have any employees after his workers compensation policy lapsed. He failed to reinstate it because he did not have employees other than himself. But now the New York state workers compensation board is trying to penalize him thousands of dollars for failure of having workers compensation insurance. Do employers have to pay workers compensation for themselves? (Seems to defeat the purpose if they do since its meant to protect employers from employee injuries and claims and one wouldn't file a claim against themself would they?). So does the NY state workers compensation board have any legal grounds for penalizing him? Thanks in advance for those of you taking your time to answer my question.