I don't see a problem with that, dmwits. I would group that into the "strategy and stuff" that is allowable within the realm of the "player" that is on the level of the game being played.
It would simply seem to me that playing the game outside of the game (i.e., attempting to use things that have nothing to do with the game as it exists essentially and as it relates to the "player" [i.e., the role assumed by a person playing the game]) would be unsportsmanlike.
Diplomacy is meant to be a test of strategic, tactical, and rhetorical capability, as TrueHeart I believe was trying to point out. It's a game to be played, for the sake of testing the mettle of the players (who assume the roles of "players") as it relates to the game, not as it relates to irrelevant rumor-mongering (there's plenty of room for relevant rumor-mongering within the game itself).
Of course, this would tend to come down to a personal conviction more than anything else as a result of the fact no site I know of has any sort of rules established concerning this particular sort of thing. However, for anything to work as best it may the rules shouldn't just be followed, but the spirit of the activity to be undertaken ought to be respected.
As I said though, all personal conviction (i.e., opinion), and therefore subjective by necessity. :)