Steve.. ".. the realities of normal life (in case, I'm glad to say that they are mostly pleasant realities, apart from this bloody bad back...)"

You mentioned years ago that you dealt with a lot of pain/discomfort almost everyday. I often wonder how such a life affects a viewpoint. I know that I get decidedly grumpy and short when *I* have aches & pains.
... but apart from speculation on that...you said " What I do feel is irritation about being a recipient of gratuitous insults, directed both at me and at others." Well... of course.. but then
   "The fact that he prevents normal (yet feisty and lusty) discussion about controversial matters is very disappointing and frustrating. Irritation, frustration, annoyance definitely, and I don't mind being direct about it.." Yes... that's clear... and others seem to agree with that approach. Then:

"(often a mistaken approach, I admit, but I am very much a head-above-parapet bloke...). "

So..your basic answer is similar to Popeye.. "I yam what I yam". It is an honest answer and no doubt a clear & accurate one. I have never encountered the "head-above-parapet" phrase before, but I think I get the gist of it. It resembles some I have heard like "I don't suffer fools gladly." and "I don't take no shit of nobody." and a woman my mother knew years ago who said "If somebody 'does me somethin', I'll stay up all night thinkin' of somethin' to do 'em back!" (she was Cajun, from New Orleans.)

I am not trying to put words in your mouth, but merely trying to suggest that almost any criticism that involves "That's just how I am, take it or leave it." is, to many either the end of the discussion or a dare. *shrug*
I fear I am treading on thin ice here. I hope you and others see that what I wish is for less confrontation and what Backwoodsman said earlier.. "ignore" If several folks say "I can't ignore trolls and I WILL call them out.", then it will continue until threads are closed and other sanctions applied.

I hope that doesn't happen...but.. 20 years of similar conflicts have gone that way...

... and that's the way *I* am...