The fun situation occurred because the infiltrator was mechanically un-identifiable, not because of any RP. The fact that the infil picked the perfect time and place was brilliance. Don't think the infiltrator ever said a word to anyone ever about it, so it's hard for me to see how it's based entirely on RP.
Politics in this game are driven by two things, role playing and prudence. Role playing in the sense that players give diplomatic consideration to events that don't necessarily affect the prudence of a matter. Prudence in the sense that, barring the influence of such aforementioned events, players engage in diplomacy in manners which they decide are most effective.
In the scenario you described, the infiltrator's attack did not affect matters of diplomatic prudence, thus the resulting diplomatic considerations paid to it can be classified as role playing. Therefore, it is entirely based on role playing.
