I replied to that thread.
OP was claiming to be working on a static HTML-serving search engine. They suggested that because it's just HTML and CSS, and that interested parties can use Inspect Element to read the network requests, that it constituted "open source".
Commenters then got on his case about not open sourcing the server backend. OP defended that choice saying they didn't want a competitor taking their code and building a company off of it that would "drive [them] out of business". Uh-huh. So, proprietary software, then. Bye.
Once you get a feel for building and owning, then you can start making more informed choices about what you really need.