It uses a self-signed certificate. Blame your web browser for overreacting.
One of the reasons I point this out is that I'm using an absolutely bog-standard setup. If I get this, so will other visitors to the site. Net result, this will kill visitor numbers.
It's no problem for me to sort it out, and I'm not bothered by it. If the author wants the muggles to read it, then s/he should be aware of the issues.
That's why I point it out.