The authors have no obligation to release anything to the public, give updates, or really care if people complain since its work they do in their free time that they happen to share with the public. Therefore no one has a right to question their motives.
Think yourself lucky you have the teaser release to play around with. Requesting betas/new releases (i.e. being a Beta-kiddie) is one of the most disrespectful things you can do (and a bannable offence, I might add since it is against the rules), and I'd imagine is very off-putting to the authors. The authors want closed beta testing, so you must respect their choice no matter what.