It was 100% supporting the claim they didn't know the first thing about the toxicity of injected aluminum in neo-nates.
No it wasn't. It only sounded like that because you quoted it out of context. What it said is that they had "scant data". Scant data is not no data, and the rest of the quote makes it clear that they do have some data and that data says that it is safe.
For example, what would be inappropriately off topic to post to LessWrong discussion about?
I couldn't find an answer in the FAQ. (Perhaps it'd be worth adding one.) The closest I could find was this:
However "rationality" can be interpreted broadly enough that rational discussion of anything would count, and my experience reading LW is compatible with this interpretation being applied by posters. Indeed my experience seems to suggest that practically everything is on topic; political discussion of certain sorts is frowned upon, but not due to being off topic. People often post about things far removed from the topics of interest. And some of these topics are very broad: it seems that a lot of material about self-improvement is acceptable, for instance.