The author of the blog posting you responded to included in his post a link to NYC Dept. of Transportation’s Traffic Rules [Title 34, chapter 4]. That document is offered on this page. Scanning through the PDF for mentions of “crosswalk”, he’s right, it prohibits parking in a crosswalk, and is silent about parking too near a crosswalk. How that interplays with state law, if state law does indeed prohibit parking within 20 feet of one, I’ve no clue.