That website is running a service that reposts twitter accounts into ActivityPub format that can be read by Mastodon... So it's not a regular Mastodon instance.
It doesn't list a responsible entity...
My interpretation is that it reposts stuff automatically, each account isn't controlled by an individual.
Right now it became overloaded so accounts aren't reachable.
I gather people built things like this for following people on Twitter…
@ruchowdh This is the software it is running. Could be that it's the creator of the software who is running that site.