But beyond that, I'm happy to overturn Titan precedent if the Titans were obviously wrong: and the ruling you quote, as you've described it, seems obviously wrong to me. No realm mergers is a very, very simple rule.
Or, maybe, the problem isn't that the ruling was wrong, but that your interpretation of the rule is wrong? In fact, I think it must be, because you're trying to claim that it's a simple rule. It is anything but a simple rule, and that's part of the problem. In fact, you're still saying that the rule is "no realm mergers", when it most emphatically is NOT "no realm mergers". Precedent demonstrates, in a few cases, that this is not the case.
Here's another one: Wasn't it IVF at the end of the fifth invasion when all the lords up and switched to Enweil? (This was facilitated by the allegiance change bug, but as we've seen before, that has no bearing on the case.) Tom's reply about it:
"They didn't really have a choice, as they are about to lose their only city. What else could they have done?" I believe they did then lose that city a turn or two later.
The no mergers rule is not intended to force people to play out a losing war to the last dregs. It is intended to prevent two otherwise viable, healthy realms from joining together to create a larger entity in which both of the two former realms will participate.
And asking the Magistrates to come up with a qualification for what makes two realms "equal" is a crazy big can of worms. How equal do they have to be? How friendly must they be?
I'm not asking you to make that decision. The rule and the "spirit of the rule" is asking it. But you cannot abdicate your responsibility to enforce it because you think that it's a can of worms, or that the resulting decision will be one you don't like.