Did you find more information? Are they safe to use again?
Support is not responding to submitted issues…Can you see if they respond to an issue you submit and report back here?
The site is no longer maintained, correct. 
I can’t speak to “safety” - ie their anonymity guarantee - but the service is functional and they’re still honoring my so-called Lifetime subscription. I use their app on my Mac and connect to their (still-shifting complement of) servers from my local Synology NAS. But there is absolutely no support that I’ve been able to unearth.
I see. So as long as the site has already been added then it still checks for the canary.
“It” doesn’t check. It just let me know that there existed a canary (and at what link it existed at).
I then checked if the canary was still up (meaning everything was okay) and found that the canary was dead.