I doubt Cardi B hovers over her phone and studiously examines every single one of the thousands of tweets a day that probably tag her. If she were to actually acknowledge a legit business deal, awesome. Until then, well, uhhh, anybody can just tag her in a tweet. It doesn't mean there is a relationship.
The twitter account has only 16 followers because it is brand new, just minted a couple days ago apparently. That's a bit of a red flag.