I think you're right to argue that Sean's article wasn't written out of any "bad faith" or positive desire to vicariously "warmonger" through the Israeli state but rather out of poor assessments on his part (I've said this in greater length elsewhere on this site), and I also think you're right to argue that the CPGB's hysterical tone - denouncing us as "abominable warmongers" who should be "driven out of the labour movement" - inhibits rational debate. Moshe Machover's not actually in the CPGB, as it happens; I'd be interested to know whether the headline was his choice or an editorial flourish on behalf of the WW.
I feel you're wrong, though, to suggest that there's something "more clear and consistent" about the CPGB's "internationalism" on the question of Iran. Our policy (agreed at our 2008 conference) is very, very clear; we oppose, and will mobilise against, any attack against Iran. At the same time, we see the Iranian regime as a brutal capitalist power in its own right with significant regional-imperialist ambitions. We will not, therefore, give any species of support to the idea than an Iranian victory in any war that did occur would be in any sense positive or something that socialists should wish for. We would (and do) back the independent agency of workers against all forces in such a war - we are, if you like, for "defeat on all sides" except that of the workers. When you strip away the hysteria and slander, that's the crux of the difference between the AWL and the CPGB; the AWL is third-campist and the CPGB is, when it comes down to it, Iranian defencist. I think they're actually decidedly unclear about this and dress it up in all kinds of pseudo-third camp rhetoric. It was a similar situation before the Iraq war, when they started off calling Iraq "paleo-imperialist" (an esoteric term but along the right lines, at least) but when the war actually started they came out with a version of the "victory to Iraq" line. You mention the Iraq war yourself and I think our position at the time was also very clear - total opposition to the war but no support whatsoever for the Ba'athist regime.
Maybe you agree with the CPGB's Iranian defencism; fine - the left should debate that issue. But "clear and consistent" is one thing their position most definitely is not.
By the by, I don't think hysterical and slanderous sectarianism is merely a product of the CPGB being on a "high horse"; I think it has more to do with their Stalinist background and their zealous refusal to actually get involved in day-to-day class struggle activity lest they catch that terribly contageous malaise "economism".