Wow, this is a terrible idea. Pointing all your domains to a service you don't control with no formal, legal contract on what they can and can't do with the domains you point at them?
Hi!
I am Dmitry Ulupov and I am running this service.
You can talk directly to me at any time. My email is dima at ulupov dot com.
What a terrible idea for me would be screwing up with people websites?
Right now the service is used by more than 5000 websites and gets just shy of 10m hits a month. If anything would happen quite a few people will know who is at fault.
But when any popular internet service goes down you are just getting formal apology from nobody.
With some ISP's caching DNS for >48 hours regardless of your TTL. And sometimes browsers caching pages for even longer. Stopping offering the service is fine. Ending up with your domain pointed to a site that isn't yours is an entirely different thing. They could run a phishing site and users wouldn't have any way of knowing.
What a terrible idea for me would be screwing up with people websites?
Right now the service is used by more than 5000 websites and gets just shy of 10m hits a month. If anything would happen quite a few people will know who is at fault. But when any popular internet service goes down you are just getting formal apology from nobody.