I still don’t see the problem. Either they’re sitting around with nothing to do, and therefor the contributions are a clear positive, or they’re neglecting the work they’re supposed to be doing and the contributions are beside the point.
If you build a software and because of a bug it breaks something, that is fine. If you deliberately change a library to make any software running it crash and you know it is used among other things by software that control nuclear plants or elevators, my guess is it will probably considered a crime in most juridictions. This regardless of the fact said software makers should test their changes.
I was taking a naive view from a theoretical point.