Now, I'm not the biggest fan of the Alternate Drop either, but I think in this case, the guys were rude to demand the "other" meal. Unfortunately with the Alternate Drop, when you don't get your preferred meal and no one else at the table is willing to swap, the protocol is to suck it up and just eat what you've received.
This is the first time I've ever heard of the Alternate Drop procedure. My feeling is that many excellent things come out of Australia, but this is not one of them !
Certainly, the function attended by the OP's father seems like an absolute train-wreck, especially in view of the demographic involved. One feels that those who organised it were, at best, utterly clueless -- the whole thing sounds as though it would make a grand sketch for an Aussie comedian...
I consider that whether those guys who were unlucky at this event were rude about it, or not -- their feeling unhappy about the matter is thoroughly understandable. Interesting that the OP and other posters opine -- sometimes strongly, as with StarFaerie in post #18 -- that the only polite thing is, if you can't swap your non-desired meal with someone else at the table, to resignedly put up with it. My sentiments are, that the world generally sees dining-out as supposed to be fun, and a pleasant experience. Unless all involved, have high-principled notions about character-building and occasional mortification of the flesh -- I don't see much sense in making the dining experience into a form of Russian roulette