I think the point to make out here, that is, the point the Taliban have jumped on, is;
Harry is a prince, in the classical sense he is a divine being, at the least he is highly regarded and loved by the default of the country he represents.
They are basically holding him to a higher moral standard, they have then jumped to their own implications of his statement and defy you to not do the same. These implications being that he compares the making of war to the playing of a video game. Essentially for fun, they say, as a prince he should know better.
Of course, like many of you here, I cannot find the position where Harry has admitted he likes to kill things, at least in a way comparable to the act of making war and not the act of playing a video game. (although those things are not being well seperated these days, refering to a recent Jimquisition, enjoying the simulation of violence a videogame presents is not even comparable, to even the concept, of the real thing.)
This still leaves Harry in a fairly difficult position, it's like comparing Hitler to an average person with genocidal tendencies that will likely never materialise.
It may be inferred that Harry himself, may, or may not, be capable of understanding the difference. Giving him the benefit of the doubt, prince or not, seems reasonable, without trying to make it personal and then discussing his own history in a impersonal manner.
He has merely stated a fondness for the way playing a game such as Call of Duty is comparable to his real-life experiences as co-pilot gunner, even helping him further understand his job, which he may be called upon to do everyday he spends in the field.
And FIFA. For that alone I'd want to drop the proverbial hammer. But that's just me.