If I'm understanding their basic message, the pitch is "we can get you cheaper prescriptions because we're a well run business that's making a rational but not exorbitant profit" and linking your branding to someone already famous for running businesses seems to be a very reasonable way to add credibility to that message.

In other words, I don't think Cuban puts his name on all businesses he's involved in like this, but for this case specifically it seems fairly obvious that using his name furthers their message.