I mean this in the most positive fashion possbile, so please don't take it as just snarky assholism:
It's that kind of thinking that would have prevented most of human achievement in the last few hundred years. If the people signing up to ride this open source rocket into space are aware of the risks, then let them take them. That doesn't mean don't put any care and testing into things, but don't turn into NASA when trying to innovate.
I wouldn't consider the knowledge of proper mission-critical testing to be of any sort mission-critical scenario. You can choose to potentially put your people at risk, but I think those decisions should be left to the actual people who will be going up, and not to a person that wants to arbitrarily contribute to it like an open source project. Small patches can have huge consequences.
It's that kind of thinking that would have prevented most of human achievement in the last few hundred years. If the people signing up to ride this open source rocket into space are aware of the risks, then let them take them. That doesn't mean don't put any care and testing into things, but don't turn into NASA when trying to innovate.