Not an IoM subject of course, but as quite a few of the "clanger" riders come on here I thought I'd ask. The forum has been locked for some sort of argument or abuse, it seems. Funny, I'd have thought a more constructive way forward would be to ban offenders or their IP addresses?

Yes, that's what we would do here, but in the past a few forums have done what you describe. That's a shame.
We rely on members behaving appropriately, or alerting us to any who don't, and on our own efforts to keep the site clean and reasonably respectful, while encouraging debate. Not always easy... believe me.
Perhaps they simply don't have the people available to keep things within limits.
Hope they get sorted out soon. Often a braek for a few days gives time to get the site in order again.
Haven't zapped anyone for ages (wistfully)... except the spammers who never get as far as the message boards.