The right place to look for consistency is at the level of moderation principles, and there I do think we've been pretty consistent over the years. Do we apply the principles optimally? No. Do we mostly apply them ok? I hope so (if not, I probably shouldn't be doing this job), and I've spent much time and energy trying to explain what the principles are.
There's another point, though, which is important here. Unfortunately it's more subtle and I'm not sure I can explain it well but I'll try:
There is a temporal decay of interestingness in any sequence of related stories. Curiosity withers under repetition, so we can't have too much repetition [2]. It follows that when you have a sequence of related stories (S1, S2, ... Sn), once S1 has had significant attention, S2 becomes less interesting until enough time has gone by. For example, this is why we tend to downweight follow-ups (https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...).
This means, though, that we can't treat related stories consistently, because how interesting they are (in HN's sense of the word) doesn't only depend on the story—it also depends on what else has been discussed recently. In itself, S2 might be a better story for HN than S1, but if they're related enough and S1 was discussed recently, then S2 becomes less interesting (not qua article, but qua HN topic) than it otherwise would have been.
If you take seriously the principle of avoiding repetition, that is how we have to treat these things, and to some extent it becomes a bit of a lottery which story (S1 or S2) comes first and thereby "wins". But if you only consider the articles themselves, this seems highly inconsistent! "Why was S1 on-topic but not S2?" is thus a common question.
From a moderation point of view, where we're more concerned with the overall functioning of the site (e.g. not having too much repetition), we actually care less about the specific stories than users do.
[editing - bear with me...]
[1] https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
[2] https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...
everyone has their own favorite topics and if i see posts with my preferred topics not get traction i am disappointed. but there are so many reasons why that may have happened, it's not worth losing sleep over, much less blame moderation.
there is no agenda here to promote the right stories and hide the wrong ones. the only goal is to promote engaging discussions. those discussions are why i am coming here. i will also admit to often checking comments first exactly because i want to see if there is an engaging discussion that i would want to join.
for this particular topic it is morbid curiosity to see if an engaging discussion will ever happen. so far it hasn't, which matches my expectations. (well, except for this sub thread about moderation)