It's a dashboard for displaying the global locations of DNS root servers and links to their authoritative organizations. Not only is this an incredibly niche site, all DNS root server information is replicated around the world by multiple organizations. Nobody uses this site to maintain their DNS trusts, it probably gets incredibly low traffic, and going out of your way to MITM it would be a lot of work for no payoff. This is a terrible target. Nobody would bother.
[0] https://www.defcon.org/images/defcon-17/dc-17-presentations/...
[1] http://arstechnica.com/tech-policy/2013/04/how-a-banner-ad-f...
Also a number of ISPs and wifi hotspots inject ads, and I know Verizon injected a tracking header based on your mobile plan.
If you're concerned about tracking cookies or headers, get a plug-in to stop it. Every website on the planet should not need to use https just because Verizon wants to make money off targeted ads.
And nobody is attacking this page to hack individuals. Of course you can. Security isn't about preventing every single possible attack from every possible angle. It's about making attacks more difficult when one is plausible or likely. Nobody will attack you through this particular website. So https is not needed to prevent a targeted attack.
The MITM argument has more merit, but even there I can't see it making much difference here given it's niche appeal. Plus given it's tech-savy bias, most people will be running a reasonably hardened system (latest patches, et al) anyway. Not the best argument against running TLS I'd admit; but still a point worth raising since the only argument for running HTTPS is to prevent malware injection.
Obviously in an ideal world everything would be served under TLS. But let's be pragmatic about which sites we bully into switching.
AFAIK website hostname is visible when using SNI.
In any case, even without the hostname header, it doesn't take much research to find a short list of possible candidates (eg https://www.virustotal.com/en/ip-address/193.0.6.136/informa...).