A policy of so-called responsible disclosure is a reasonable approach to take when dealing with an established product/service that contains a minor vulnerability, something potentially dangerous but unlikely to be exploited in the immediate future with serious negative effects.
In this case, we appear to have a new project run by people who don't know what they're doing, with a glaring vulnerability that had presumably already compromised 80+ people's sensitive credentials and in turn who knows what other sensitive information. Bringing it down as fast as humanly possible and loudly so no-one else gets damaged in the meantime is entirely justified in a case like this.