Maybe I watched a different episode then the people who rated this episode 1 and 1.5, but thats way to low. And I don´t agree with the reasoning either. For example, the boy was 18 but looked much younger. The noted that in the episode. And as far as the `mission of NCIS´goes. They explained it very well i think. You are right it isn´t a case for them, but as we later get to know, Vance used his position to influence the case. I think the writers wrap up to the season final that will have to do with Vance and the upcoming of Barret.
As far as the action, yes there was a lack of it, but if you need that you need to wacht NCIS: LA (which I like to by the way, but doesn´t nearly reaches the level of NCIS). I think you need excelent writing skills to pull, an episode like this, of. And they did well.