^Look at my avatar - he meant it alright regardless of what he had up his sleeve, you could see the anger build in his face - who's benefit was that 'act' for?
Have you ever seen Kirk lose his temper like that? I mean, in TOS or something? By that sort of thing, Kirk was overreacting, and while Shatner may be an over-actor, this was way too much ham. No, I am sure that Kirk was pretending to be frustrated.