It says that you have the role on discord and a role is not required to access the BST forum here on the website. Since you had the BST role on discord before the new MarketPlace rules you could have posted your sale without making a Forums account.
Yeah, if you're normally on the discord and want to be in the BST group we require that you have a forums account too so we can match it up to the discord. It's mainly there to help us weed out bad actors who we've had instances of people joining discord and ripping people off. The Allspark is a Transformers community, but we've always been a community first and foremost.