(unless the ninjas are sailor-ninjas on a navy ship - for some reason, despite the fact that any Japanese power with a navy never employed ninjas as far as has been recorded)

Was not my counterfactual scenario. It was someone else describing a counterfactual where ninjas are travelling by sea to a ninja-convention. My only contribution there was to (implicitly) assert that the counterfactualising operation that preserves the most probability mass to produce that scenario would not result in ninjas travelling on unarmed ships.

To say that anyone who doesn't think real pirates aren't "ridiculously worse [in an unspecified manner] than ninjas is not thinking well at all" seems quite absurd to me, and smacks of "ninja fanboyism".

I had never really considered it before daenerys proposed the idea of actually considering the question. I don't particularly accept the charge "in an unspecified manner" but I certainly haven't gone into detail. It roughly pertains to how one reasons about counter-factual and hypothetical situations. One can either take the counterfactual as an excuse to make up whatever story suits your position or you can apply the counterfactualizing operation in a manner that preserves the most probability mass.

I consider this question a valid diagnostic tool in that regard. In fact I went ahead and used it as such. I made this very meta-claim on facebook and when anyone disagreed I unfriended them. I call it either "evaporative cooling of styles of thinking in my chosen peers" or "being grumpy and getting rid of people who are likely to say annoying and wrong things in the future".