I am the maker of SnipCSS. https://www.snipcss.com
Just like with other tools such as yt-dlp, the user is required to use it responsibly. As long as you don't copy text/images/svg, the only issue is going to be "trade dress" infringement since CSS styles are not copyrightable. (not a lawyer so this isn't legal advice)
Strange that this post made it to HN because I'm also releasing a Tailwind conversion this week. https://x.com/SnipCSS/status/1853586090164420639 I believe mine will be much better based on the blog post about this tool.