I am not ignoring this but I will not engage fully with all of it because to do so effectively would require us to write several posts worth of background to even be using the same meaning for words.

Does this mean people find this an important topic and would like to discuss it, but will now forever avoid the question? That would indeed be a rationality fail.

I agree, and rather hope not.

Certainly there's no requirement on anybody to answer any questions if they don't feel like it. But, how should I put this... it's certainly a worrying sign if they can be deflected from a question they'd otherwise consider, simply because the wrong person also happens to ask it.

I would not be quite as worried and would perhaps frame it slightly differently. I may share an underlying concern with maintaining an acceptable 'bullshit to content' ratio. Things like ignoring people or arguments can sometimes fall into that bullshit category and oft times are a concern to me. I think I have a somewhat different conception than you when it comes to "times when ignoring stuff is undesirable".