You’re right of course, it was all legal so there is no problem. Just don’t want to get somehow accidentally associated with anything that isn’t. Apparently the cofounder of the site was also the founder of some hacking site, so it looks bad by association.
I don’t know how big or popular sellix was outside of there and here as I have never used it for anything other than VR funscripts but I imagine lots of people used it for normal legit ecommerce too.