This may apply to other fandoms as well, except the first one. That’s all Sailor Moon.
The Logic Question
Before you call out someone’s headcanon or fanfic for being “impossible” and therefore illogical, here are three things to remember about the world of Sailor Moon:
1. Magic. This is a world of magic.Unless the person is writing a magic-less AU, remember that this is a world of magic.
This is a world where someone can canonically stop aging around 6-7 for close to 900 years and be expected to resume aging normally at some point.
This is a world where a crystal can canonically live inside person until their pure tears cry it out.
Honestly, that should be enough. Because if you really feel like “but that’s impossible, so your argument is illogical” or “that’s impossible so it ruined the whole fanfic for me” stands up with those two canonical realities, then maybe just don’t comment.
2. Advanced Technology from an Advanced but All but Forgotten Ancient Society. They may not have access to all of it, but if it’s a technological/scientific issue that our scientists feel like they are close to unlocking, you can assume they already did in the SilMil.
3. Mizuno Ami. Ami has access to both 1 & 2, is a genius, and has access to at least some of her SilMil-prior-life memories.
So what exactly is impossible and therefore illogical?
The Opinion vs. Trying to Make their Headcanon/Interpretation of Canon Law for the Whole Fandom Question
If the person is just stating an opinion, even if it’s a strongly worded opinion, there is no need for you to protect the whole of the fandom from their headcanon.
Either the Sailor Moon fandom is a wide open and welcoming fandom or it’s not. I really want it to be. Disagree with other people’s headcanons, but be respectful about it. If you can’t do so respectfully and using “I” statements, then maybe you should not comment at all.
Are They Being Hateful or Bullying?
Is the person whose headcanon/interpretation of canon you disagree with, no matter how vehemently, attacking people who disagree with them? Are they being hateful toward those who interpret it differently? Are they calling people who “read” the canon differently from themselves hateful or slandering terms? Are they seeking out people with different interpretations to specifically attack? Are they seeking out positive posts about different opinions to jump on and rage about how horrible anyone who thinks such a thing is?
If no, and you feel the need to rip their headcanon (and thus them) a new one, then you are probably the bully.