There is a risk downloading the text. Does it warrant a signature? I don't think so.
When you hand out candy on Halloween you could include a digital signature with each piece you hand out. People receiving the candy would have more confidence it came from you, and not a bad guy wearing a mask, sitting on your front porch impersonating you.
Does everything need signatures? The stakes of accepting candy are much higher simple raw text.
Edit: to be fair, I mean in this specific case. And I know they _could_ be. But are they?
This is a common misconception. If a page is using http, an attacker could add a sign-up form, a login form, a payment form, a malware download etc. or anything they want to the page to steal entered data or just redirect you to another malicious site, anything they want.
Google's war on http is misguided, dumb, and wasteful.
I love that website and didn't know about that until now. Now I love it even more.
I opened the link from inside Firefox just fine. YMMV.