That clone website seems to be not finished yet he forgot to put other pages like faq, news, and language choices.
You are right, clone sites never go away they will continue to be made when there are mixers that become new in popularity and that includes the sinbad mixer.
There is another one I found recently cloned site with domain name
mixersinbad.io but here have added FAQ, news and language options but still they have a different email from the original.
I believe this clone was made by other competitors who trying to hijack traffic.
It is likely the same as what happened to Chipmixer there are lots of fake Chipmixer before.
I think Sinbad should buy almost all domains near on their domain name to avoid this phishing and cloning.
I don't know whether this is really their competition or there are scammers who deliberately make it without involving the original, but what is clear is that every time there is a popular mixing site there will be an imitation site and including sinbad which is now known on forums as popular mixing.
This won't even be far from the previous mixer scam, which has been cloned a lot, but will the official Sinbad take this action so that its name remains clean from clone sites?