Active support either inside the site chat or in email form as long as there is someone who's responding
and giving you an update will give you some hope if you have any issue with your balance, it's not easy to trust but if you see that
the site or the representatives are willing to assist you, then it gives some enlighten to your concern.
An active and responsive customer support may help you to solve some issues or give you hope, as you said, if your money is stuck. But, unfortunately, it's not an indicator that the casino can be trusted. It can be in a perfect world, but in reality and based on my own experience I can say that it's not.
What I have noticed is that most scam services or phishing websites usually have a very active customer support (most likely the scammers himself) while most trusted and long standing services are known for their bad customer service.