Okay, I'm sick of the fearmongering:
http://www.corecharity.org.uk/The-Hazards-of-Swallowing-Glass.html
Highlights:
"Small pieces can travel right through the bowel and be passed normally without problems."
"Sharp objects such as glass fragments might be expected to cause damage but rarely do so because of the gentle way in which the bowel handles them."
"Ground glass, despite its reputation in thrillers, has no serious effect on the bowel."
They also say if you think you might have swallowed glass that you should see a doctor, but they
also say that the treatment is usually just to wait and see. They also point out that most people, you know, notice if there is glass in their mouth and don't swallow it.
I think the decision to dump it out of an abundance of caution is totally defensible, but I also think the decision NOT to dump it is at least as defensible. Let's look at the chain of events that would have to occur for this to actually cause serious injury:
thecraft would have to have missed one or more of the shards, which due to the setup, he or she thinks didn't happen.
The shard would then have to get sucked up through the siphon when racking to the bottling bucket, rather than just resting harmlessly in the trub.
You'd then have to drink the shard without noticing it when you poured the beer into the glass.
And then even after that, it would be extremely rare for it to cause even minor internal bleeding.
The odds of that whole chain of events coming to pass are TINY. Now, if you are of the mindset that even the tiniest risk is not tolerable for the modest benefit of getting to keep the batch, then that's fine. But the risk is pretty damn small.