I am not in any way an anti-vaxxer, my own child has been vaccinated according to the standard protocols in my country, and I agree that NatPhilosopher should have mentioned that alongside the scary-sounding stuff s/he quoted the quoted sources contain statements that aluminium-based vaccines appear to be safe, and that not doing so is dishonest.
BUT it seems to me (as far as the material you've quoted goes; of course there may be more that points the other way) that NatPhilosopher is correct to say that this report suggests that the safety of injected aluminium salts is poorly understood, particularly with respect to long-term consequences as opposed to acute adverse events.
NatPhilosopher may very well be dead wrong, and indeed my guess is that s/he is. But the material s/he quoted doesn't seem to me much less worrying with context than without.
I wasn't an anti-vaxxer till I started reading the scientific literature on it. I vaxxed my first 2 kid too.
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.