I would make two points:
Firstly, now that the problem has arisen, for Ryanair not to immediately accept British Military ID's is insulting to both the armed services and all the ex-servicemen and women in the UK (and the Republic). It is also insulting to the elected government of the UK, not to mention everyone who places a value on the armed forces. It certainly conflicts with most peoples logic and commonsense.
Secondly, to score points off some inexperienced young trooper so that Ryanair staff can swagger and preen at their cleverness and omnipotence beggars belief. Have they no sense of the outrage that will take place if, (heaven forbid) this young man should be injured or killed in the forthcoming coflict? You don't have to be a journalist to imagine the sort of headline that will be written should this happen.
Ryanair! you have embarrassed the rest of us in the aviation family. Perhaps you should consider who it is that provides the freedom that you operate under...even though they don't charge you much for the service!