Threads is a buggy mess. It has been impossible to create an account on the platform in Europe for months because of a broken authentication system. Even if you do manage to create an account, you have a decent chance of a random and arbitrary ban.
Usually posts from banned accounts aren't visible outside of that account.
From what the post mentions, I'd presume the accounts were banned for promoting commercial content without an enterprise account. Most social media platforms are more concerned about non-enterprise accounts being used for promotion than they are whether or not those accounts are bots, as promotional content is the main source of income for most social media platforms. A premium but not enterprise account usually only costs a few dollars to a few tens of dollars per month, but an enterprise account can be in the thousand-plus dollar range.