It worked fine for me, and judging from comments on this page that respond to the article not just the title, for many others.

If you see this message in Firefox for many sites (try some random sites you rarely visit) it's probably a local problem such as "Anti-Virus" software or a "security" appliance helpfully making stuff unsafe. Get rid of them if possible.

It is possible that, as the message says, there's actually "Possible Security Issue" just for you, or some subset of visitors, and we can't really help you diagnose that. Maybe your ISP, or your government, or that nerd neighbour kid who said she'd fix your WiFi are trying to snoop you. But probably not.

It's also possible the server hosting this went a bit haywire maybe under the load. It's clearly on some cheap bulk host and those can be a bit flaky.

I got that, but it was from the office firewall considering it to be a malicious site

My corporate network uses Cisco and it seems to block any newly set up website.

Synchronize your system clock and attempt again.