Isn't there a clause to opensource for "unmaintained, delivered as is?"

Open source licenses dictate permission to access to the source code, distribute it, change it, and distribute those changes. They say nothing about how the developer needs to maintain the project or provide support. There are FOSS licenses that mention warranties and support but that isn't exclusive to FOSS, plenty of closed source products come with zero support as well. Support generally comes into play when you pay money for something, which again, is completely separate from FOSS licenses.