Not that unsafe in this particular case. The original website was set up with a secured link (https). That requires a security certificate valid for the web domain australinea.com (which is not much of a big deal in itself, anyone can create a self-signed certificate). However, now that that site no longer exists, the page request gets forwarded to the hosting company which has a certificate valid for itself (hosting-services.net.au). So the warning is only your browser telling you that the certificate it received from the web site does not match the name of the website. This can be serious if you are going to log in somewhere or do something secretive, but opening a supposedly publicly available news web page is fine.
If you ignore that mismatch and push through, you get a 404 web page not found message. Now while it is possible for a particular web page to get lost because of culling or website restructure, it is extremely unlikely in the normal course of events for the domain home page (
https://www.australinea.com/) to disappear as well. ie, you may not be surprised if a particular webpage that you bookmarked a year ago from news.com.au to give a 404 not found message, but you would never expect news.com.au home page to ever disappear while that company still exists.
If I was to follow the money, I would suspect that someone created a fake news web site to manipulate the stock price. Very unethical and very illegal.