Thank you for that information!
Make sure you enable your 2FA authentication anyways to become safer than before at
Primedice.comSo in case you log at some pishing site you still have security on the main domain.
Reading his post where he says
I'm not concerned about how you plan to use it
Is direct proof that he probably bought it for phishing reasons. Looking at the WHOIS info it looks like he bought this domain shortly after Primedice.com was registered in 2013. So is there someone buying up all these domains so 5 years later if the site still exists they can use it for spoofing reasons?
Did you try and reach out to the individual to purchase the domain name directly? Maybe the cost won't be too large? Or maybe get your lawyer involved due to trademark reasons.