I think the page has changed? It doesn't say this now.... also your link to web archive seems to be a save link rather than a link to the captured site
The HN link is to a lower section of the page; if you scroll up you can see a section called "What is an open source ticketing system?". Or, just search for "What is an open source ticketing system?" and you can see it in a part above.
I think they have changed it now. You may be still seeing the locally cached previous version (as I was too until I realised).
You are right! I hard refreshed and it's gone. It seems the whole page has been removed, luckily it's captured in the Internet Archive as it was:
Take a look at xerxes901's comment in this post. Looks like they got through to someone internally. And their comment history checks out; it appears they do with for or with Zendesk.