Yo Richard,
Classic story about the hotel in Gondor. Was it the Circle Hotel? I was there a couple of months back and they were a bit dodgy in the pricing and room availability.
Like you, I am loath to get ripped off and hate setting bad precedents for future riders. I like to think that most times I try to act pretty reasonably even when the situation may require a bit of unreasonable action, only because I try to think about the next rider coming along and would hate to have burned any bridges for them. Must be my age or something, but I do tend to think of all of us ambassadors of all motorcyclists as well as of our own country.
I think that we must have left Ethiopia with different impressions. Legally, you could be correct, with enough time and money you might be able to prove that it wasn't your fault and get away without paying much, if anything. Realistically, I believe that this effort would be too much for most of us to put up with and the laws of locals vs. foreigners and of frontier justice would rule the day. Don't get me wrong, I'm the type of person who has refused to pay the 4 birr (45 cents) for a couple of bananas in Gondor because I know that the locals price for a whole kilo is 4 birr. But when the crowd gathers around me with their wooden clubs or machetes or AK47s, I would negotiate with the best of them, feign ignorance, pretend not to understand them and put up enough of a fuss to figure out how serious they were and where the real rate stood. Eventually, you would get a good sense for risk, and more likely than not, because they have much, much more time and patience than the majority of us foreigners, pay an amount I could live with. I don't know if it would be less than the $250 he mentioned, but I would like to hope so, impossible to say though without knowing them and the situation.
On the topic of Irishmen, I met a fellow from Ireland on the same trip who had ridden to Syria from South East Asia. He was clearly insane enough to like motorcycling across continents, which made him a friend of mine, loved

, which made him an excellent travelling companion and with 48 hours notice almost changed his plans to ride the length of Africa instead of heading back across Europe. Carzy Irishmen are always welcome along for the ride, now I just know to wait for them in the next pub while they negotiate for the price of the livestock that they just hit