I don't think it's fair to expect an airline to prepare 3 meals for just 1 passenger. I don't eat beef also, but I never felt the need to request a no beef meal because they would normally have 2 non-beef options in the menu.
If you order a special meal but don't like it you should wait till all other pax have chosen their meals before you get to have what's left. Otherwise it's not fair.
We did not order a special meal, more a special requirement of no beef meal, if there was a beef meal (which there wasn't) on the menu for that flight I would expect my mother to be asked 1st what would she like from the 2 other options available but that did not happen, she was given a meal that Cathay thought was suitable.
Maybe I was going over the top to suggest an extra of each meal but...
There has been occassions when travelling in business/premium/economy where I and others have been in the middle of the cabin and they had run out of 1 of the 3 choices of meals and/or desserts, now I understand that if I was asked or served last. Also I've seen passengers turn down the meal or go straight to sleep (and what about the no shows) so surely that would increase the chance of the meal or dessert that I or my mother or passengers would want or even allowed to have 2 meals or desserts?